Structure sigma_algebraTheory


Source File Identifier index Theory binding index

signature sigma_algebraTheory =
sig
  type thm = Thm.thm
  
  (*  Definitions  *)
    val algebra_def : thm
    val binary_def : thm
    val disjoint_family_on : thm
    val disjointed : thm
    val dynkin_def : thm
    val dynkin_system_def : thm
    val measurable_def : thm
    val prod_sets_def : thm
    val prod_sigma_def : thm
    val restrict_algebra_def : thm
    val ring_def : thm
    val semiring_def : thm
    val set_liminf_def : thm
    val set_limsup_def : thm
    val sigma_algebra_alt : thm
    val sigma_algebra_def : thm
    val sigma_def : thm
    val sigma_function_def : thm
    val sigma_functions_def : thm
    val smallest_ring_def : thm
    val space_def : thm
    val subset_class_def : thm
    val subsets_def : thm
  
  (*  Theorems  *)
    val ALGEBRA_ALT_INTER : thm
    val ALGEBRA_COMPL : thm
    val ALGEBRA_COMPL_SETS : thm
    val ALGEBRA_DIFF : thm
    val ALGEBRA_EMPTY : thm
    val ALGEBRA_FINITE_INTER : thm
    val ALGEBRA_FINITE_INTER' : thm
    val ALGEBRA_FINITE_UNION : thm
    val ALGEBRA_IMP_RING : thm
    val ALGEBRA_IMP_SEMIRING : thm
    val ALGEBRA_INTER : thm
    val ALGEBRA_INTER_SPACE : thm
    val ALGEBRA_RESTRICT : thm
    val ALGEBRA_RESTRICT' : thm
    val ALGEBRA_SETS_COLLECT_CONST : thm
    val ALGEBRA_SETS_COLLECT_IMP : thm
    val ALGEBRA_SETS_COLLECT_NEG : thm
    val ALGEBRA_SINGLE_SET : thm
    val ALGEBRA_SPACE : thm
    val ALGEBRA_UNION : thm
    val BIGINTER_OVER_INTER_L : thm
    val BIGINTER_OVER_INTER_R : thm
    val BIGINTER_PAIR : thm
    val BIGUNION_IMAGE_BIGUNION_IMAGE_UNIV : thm
    val BIGUNION_IMAGE_COUNT_IMP_UNIV : thm
    val BIGUNION_IMAGE_UNIV_CROSS_UNIV : thm
    val BIGUNION_OVER_DIFF : thm
    val BIGUNION_OVER_INTER_L : thm
    val BIGUNION_OVER_INTER_R : thm
    val BIGUNION_disjointed : thm
    val BINARY_RANGE : thm
    val COMPL_BIGINTER : thm
    val COMPL_BIGINTER_IMAGE : thm
    val COMPL_BIGUNION : thm
    val COMPL_BIGUNION_IMAGE : thm
    val DIFF_INTER_PAIR : thm
    val DINTER_IMP_FINITE_INTER : thm
    val DISJOINT_CROSS_L : thm
    val DISJOINT_CROSS_R : thm
    val DISJOINT_RESTRICT_L : thm
    val DISJOINT_RESTRICT_R : thm
    val DUNION_IMP_FINITE_UNION : thm
    val DYNKIN : thm
    val DYNKIN_LEMMA : thm
    val DYNKIN_MONOTONE : thm
    val DYNKIN_SMALLEST : thm
    val DYNKIN_STABLE : thm
    val DYNKIN_STABLE_LEMMA : thm
    val DYNKIN_SUBSET : thm
    val DYNKIN_SUBSET_SIGMA : thm
    val DYNKIN_SUBSET_SUBSETS : thm
    val DYNKIN_SYSTEM_ALT : thm
    val DYNKIN_SYSTEM_ALT_MONO : thm
    val DYNKIN_SYSTEM_COMPL : thm
    val DYNKIN_SYSTEM_COUNTABLY_DUNION : thm
    val DYNKIN_SYSTEM_DUNION : thm
    val DYNKIN_SYSTEM_EMPTY : thm
    val DYNKIN_SYSTEM_INCREASING : thm
    val DYNKIN_SYSTEM_SPACE : thm
    val DYNKIN_THM : thm
    val FINITE_TWO : thm
    val GBIGUNION_IMAGE : thm
    val GEN_COMPL_BIGINTER : thm
    val GEN_COMPL_BIGINTER_IMAGE : thm
    val GEN_COMPL_BIGUNION : thm
    val GEN_COMPL_BIGUNION_IMAGE : thm
    val GEN_COMPL_FINITE_INTER : thm
    val GEN_COMPL_FINITE_UNION : thm
    val GEN_COMPL_INTER : thm
    val GEN_COMPL_UNION : thm
    val GEN_DIFF_INTER : thm
    val IMAGE_SIGMA : thm
    val IMAGE_SIGMA_ALGEBRA : thm
    val INCREASING_TO_DISJOINT_SETS : thm
    val INCREASING_TO_DISJOINT_SETS' : thm
    val INTER_BINARY : thm
    val INTER_SPACE_EQ1 : thm
    val INTER_SPACE_REDUCE : thm
    val IN_DYNKIN : thm
    val IN_LIMINF : thm
    val IN_LIMSUP : thm
    val IN_MEASURABLE : thm
    val IN_MEASURABLE_COMP : thm
    val IN_MEASURABLE_CONG : thm
    val IN_MEASURABLE_EQ : thm
    val IN_MEASURABLE_PROD_SIGMA : thm
    val IN_PROD_SETS : thm
    val IN_SIGMA : thm
    val IN_SPACE_PROD_SIGMA : thm
    val LIMSUP_COMPL : thm
    val LIMSUP_DIFF : thm
    val LIMSUP_MONO_STRONG : thm
    val LIMSUP_MONO_STRONGER : thm
    val LIMSUP_MONO_WEAK : thm
    val MEASUBABLE_BIGUNION_LEMMA : thm
    val MEASURABLE_BIGUNION_PROPERTY : thm
    val MEASURABLE_COMP : thm
    val MEASURABLE_COMP_STRONG : thm
    val MEASURABLE_COMP_STRONGER : thm
    val MEASURABLE_DIFF_PROPERTY : thm
    val MEASURABLE_FST : thm
    val MEASURABLE_I : thm
    val MEASURABLE_LEMMA : thm
    val MEASURABLE_LIFT : thm
    val MEASURABLE_PAIR : thm
    val MEASURABLE_PROD_SIGMA : thm
    val MEASURABLE_PROD_SIGMA' : thm
    val MEASURABLE_SIGMA : thm
    val MEASURABLE_SIGMA_PREIMAGES : thm
    val MEASURABLE_SND : thm
    val MEASURABLE_SUBSET : thm
    val MEASURABLE_UP_LIFT : thm
    val MEASURABLE_UP_SIGMA : thm
    val MEASURABLE_UP_SUBSET : thm
    val POW_ALGEBRA : thm
    val POW_SIGMA_ALGEBRA : thm
    val PREIMAGE_SIGMA : thm
    val PREIMAGE_SIGMA_ALGEBRA : thm
    val RING_BIGUNION : thm
    val RING_DIFF : thm
    val RING_DIFF_ALT : thm
    val RING_EMPTY : thm
    val RING_FINITE_BIGUNION1 : thm
    val RING_FINITE_BIGUNION2 : thm
    val RING_FINITE_INTER : thm
    val RING_FINITE_INTER' : thm
    val RING_FINITE_UNION : thm
    val RING_FINITE_UNION_ALT : thm
    val RING_IMP_SEMIRING : thm
    val RING_INSERT : thm
    val RING_INTER : thm
    val RING_SETS_COLLECT_FINITE : thm
    val RING_SPACE_IMP_ALGEBRA : thm
    val RING_UNION : thm
    val SEMIRING_DIFF : thm
    val SEMIRING_DIFF_ALT : thm
    val SEMIRING_EMPTY : thm
    val SEMIRING_FINITE_INTER : thm
    val SEMIRING_FINITE_INTER' : thm
    val SEMIRING_INTER : thm
    val SEMIRING_PROD_SETS : thm
    val SEMIRING_PROD_SETS' : thm
    val SEMIRING_SETS_COLLECT : thm
    val SETS_TO_DISJOINT_SETS : thm
    val SETS_TO_DISJOINT_SETS' : thm
    val SETS_TO_INCREASING_SETS : thm
    val SETS_TO_INCREASING_SETS' : thm
    val SIGMA_ALGEBRA : thm
    val SIGMA_ALGEBRA_ALGEBRA : thm
    val SIGMA_ALGEBRA_ALT : thm
    val SIGMA_ALGEBRA_ALT_DISJOINT : thm
    val SIGMA_ALGEBRA_ALT_MONO : thm
    val SIGMA_ALGEBRA_ALT_SPACE : thm
    val SIGMA_ALGEBRA_COMPL : thm
    val SIGMA_ALGEBRA_COUNTABLE_INT : thm
    val SIGMA_ALGEBRA_COUNTABLE_INT' : thm
    val SIGMA_ALGEBRA_COUNTABLE_UN : thm
    val SIGMA_ALGEBRA_COUNTABLE_UN' : thm
    val SIGMA_ALGEBRA_COUNTABLE_UNION : thm
    val SIGMA_ALGEBRA_DIFF : thm
    val SIGMA_ALGEBRA_EMPTY : thm
    val SIGMA_ALGEBRA_ENUM : thm
    val SIGMA_ALGEBRA_FINITE_INTER : thm
    val SIGMA_ALGEBRA_FINITE_INTER' : thm
    val SIGMA_ALGEBRA_FINITE_UNION : thm
    val SIGMA_ALGEBRA_FN : thm
    val SIGMA_ALGEBRA_FN_BIGINTER : thm
    val SIGMA_ALGEBRA_FN_DISJOINT : thm
    val SIGMA_ALGEBRA_IMP_DYNKIN_SYSTEM : thm
    val SIGMA_ALGEBRA_INTER : thm
    val SIGMA_ALGEBRA_PROD_SIGMA : thm
    val SIGMA_ALGEBRA_PROD_SIGMA' : thm
    val SIGMA_ALGEBRA_PROD_SIGMA_WEAK : thm
    val SIGMA_ALGEBRA_RESTRICT : thm
    val SIGMA_ALGEBRA_RESTRICT' : thm
    val SIGMA_ALGEBRA_RESTRICT_SUBSET : thm
    val SIGMA_ALGEBRA_SIGMA : thm
    val SIGMA_ALGEBRA_SIGMA_UNIV : thm
    val SIGMA_ALGEBRA_SPACE : thm
    val SIGMA_ALGEBRA_SUBSET_SPACE : thm
    val SIGMA_ALGEBRA_UNION : thm
    val SIGMA_CONG : thm
    val SIGMA_MEASURABLE : thm
    val SIGMA_MONOTONE : thm
    val SIGMA_POW : thm
    val SIGMA_PROPERTY : thm
    val SIGMA_PROPERTY_ALT : thm
    val SIGMA_PROPERTY_DISJOINT : thm
    val SIGMA_PROPERTY_DISJOINT_LEMMA : thm
    val SIGMA_PROPERTY_DISJOINT_LEMMA1 : thm
    val SIGMA_PROPERTY_DISJOINT_LEMMA2 : thm
    val SIGMA_PROPERTY_DISJOINT_WEAK : thm
    val SIGMA_PROPERTY_DISJOINT_WEAK_ALT : thm
    val SIGMA_PROPERTY_DYNKIN : thm
    val SIGMA_REDUCE : thm
    val SIGMA_RESTRICT : thm
    val SIGMA_SIMULTANEOUSLY_MEASURABLE : thm
    val SIGMA_SMALLEST : thm
    val SIGMA_STABLE : thm
    val SIGMA_STABLE_LEMMA : thm
    val SIGMA_SUBSET : thm
    val SIGMA_SUBSET_SUBSETS : thm
    val SMALLEST_RING : thm
    val SMALLEST_RING_OF_SEMIRING : thm
    val SMALLEST_RING_SUBSET_SUBSETS : thm
    val SPACE : thm
    val SPACE_DYNKIN : thm
    val SPACE_PROD_SIGMA : thm
    val SPACE_SIGMA : thm
    val SPACE_SMALLEST_RING : thm
    val SUBSET_DIFF_DISJOINT : thm
    val SUBSET_DIFF_SUBSET : thm
    val SUBSET_INTER_SUBSET_L : thm
    val SUBSET_INTER_SUBSET_R : thm
    val SUBSET_MONO_DIFF : thm
    val SUBSET_RESTRICT_DIFF : thm
    val SUBSET_RESTRICT_L : thm
    val SUBSET_RESTRICT_R : thm
    val SUBSET_TWO : thm
    val TRACE_SIGMA_ALGEBRA : thm
    val UNION_BINARY : thm
    val UNION_TO_3_DISJOINT_UNIONS : thm
    val UNIV_SIGMA_ALGEBRA : thm
    val algebra_alt : thm
    val algebra_alt_inter : thm
    val algebra_alt_union : thm
    val algebra_finite_space_imp_sigma_algebra : thm
    val algebra_finite_subsets_imp_sigma_algebra : thm
    val count1_def : thm
    val count1_numseg : thm
    val disjoint_family_def : thm
    val disjoint_family_disjoint : thm
    val disjoint_family_on_def : thm
    val disjoint_family_on_iff_disjoint : thm
    val disjoint_family_on_imp_disjoint : thm
    val disjointed_subset : thm
    val finite_decomposition : thm
    val finite_decomposition_simple : thm
    val finite_disjoint_decomposition : thm
    val finite_disjoint_decomposition' : thm
    val finite_enumeration_of_sets_has_max_non_empty : thm
    val infinitely_often_lemma : thm
    val infinity_bound_lemma : thm
    val prod_sigma_alt_sigma_functions : thm
    val prod_sigma_alt_sigma_functions' : thm
    val restrict_algebra_SUBSET : thm
    val restrict_algebra_reduce : thm
    val restrict_algebra_reduce' : thm
    val ring_alt : thm
    val ring_alt_pow : thm
    val ring_alt_pow_imp : thm
    val ring_and_semiring : thm
    val ring_disjointed_sets : thm
    val semiring_alt : thm
    val set_limsup_alt : thm
    val sigma_algebra_alt_eq : thm
    val sigma_algebra_alt_pow : thm
    val sigma_algebra_eq_alt : thm
    val sigma_algebra_iff2 : thm
    val sigma_algebra_restrict_algebra : thm
    val sigma_algebra_sigma_function : thm
    val sigma_algebra_sigma_functions : thm
    val sigma_algebra_sigma_sets : thm
    val sigma_function_alt_sigma_functions : thm
    val sigma_function_subset : thm
    val sigma_functions_1 : thm
    val sigma_functions_subset : thm
    val sigma_sets_BIGINTER : thm
    val sigma_sets_BIGINTER2 : thm
    val sigma_sets_BIGUNION : thm
    val sigma_sets_basic : thm
    val sigma_sets_cases : thm
    val sigma_sets_compl : thm
    val sigma_sets_empty : thm
    val sigma_sets_eq : thm
    val sigma_sets_fixpoint : thm
    val sigma_sets_ind : thm
    val sigma_sets_into_sp : thm
    val sigma_sets_least_sigma_algebra : thm
    val sigma_sets_rules : thm
    val sigma_sets_sigma : thm
    val sigma_sets_strongind : thm
    val sigma_sets_subset : thm
    val sigma_sets_superset_generator : thm
    val sigma_sets_top : thm
    val sigma_sets_union : thm
    val space_sigma_function : thm
    val space_sigma_functions : thm
    val subset_class_POW : thm
    val tail_countable : thm
    val tail_not_empty : thm
    val trivial_algebra_of_space : thm
    val trivial_algebra_of_two_points : thm
    val trivial_algebra_of_two_sets : thm
(*
   [nets] Parent theory of "sigma_algebra"
   
   [algebra_def]  Definition
      
      ⊢ ∀a. algebra a ⇔
            subset_class (space a) (subsets a) ∧ ∅ ∈ subsets a ∧
            (∀s. s ∈ subsets a ⇒ space a DIFF s ∈ subsets a) ∧
            ∀s t. s ∈ subsets a ∧ t ∈ subsets a ⇒ s ∪ t ∈ subsets a
   
   [binary_def]  Definition
      
      ⊢ ∀a b. binary a b = (λx. if x = 0 then a else b)
   
   [disjoint_family_on]  Definition
      
      ⊢ ∀a s.
          disjoint_family_on a s ⇔
          ∀m n. m ∈ s ∧ n ∈ s ∧ m ≠ n ⇒ a m ∩ a n = ∅
   
   [disjointed]  Definition
      
      ⊢ ∀A n.
          disjointed A n =
          A n DIFF BIGUNION {A i | i ∈ {x | 0 ≤ x ∧ x < n}}
   
   [dynkin_def]  Definition
      
      ⊢ ∀sp sts.
          dynkin sp sts =
          (sp,BIGINTER {d | sts ⊆ d ∧ dynkin_system (sp,d)})
   
   [dynkin_system_def]  Definition
      
      ⊢ ∀d. dynkin_system d ⇔
            subset_class (space d) (subsets d) ∧ space d ∈ subsets d ∧
            (∀s. s ∈ subsets d ⇒ space d DIFF s ∈ subsets d) ∧
            ∀f. f ∈ (𝕌(:num) → subsets d) ∧
                (∀i j. i ≠ j ⇒ DISJOINT (f i) (f j)) ⇒
                BIGUNION (IMAGE f 𝕌(:num)) ∈ subsets d
   
   [measurable_def]  Definition
      
      ⊢ ∀a b.
          measurable a b =
          {f |
           f ∈ (space a → space b) ∧
           ∀s. s ∈ subsets b ⇒ PREIMAGE f s ∩ space a ∈ subsets a}
   
   [prod_sets_def]  Definition
      
      ⊢ ∀a b. prod_sets a b = {s × t | s ∈ a ∧ t ∈ b}
   
   [prod_sigma_def]  Definition
      
      ⊢ ∀a b.
          a × b =
          sigma (space a × space b) (prod_sets (subsets a) (subsets b))
   
   [restrict_algebra_def]  Definition
      
      ⊢ ∀A sp.
          restrict_algebra A sp =
          (sp ∩ space A,IMAGE (λa. a ∩ sp) (subsets A))
   
   [ring_def]  Definition
      
      ⊢ ∀r. ring r ⇔
            subset_class (space r) (subsets r) ∧ ∅ ∈ subsets r ∧
            (∀s t. s ∈ subsets r ∧ t ∈ subsets r ⇒ s ∪ t ∈ subsets r) ∧
            ∀s t. s ∈ subsets r ∧ t ∈ subsets r ⇒ s DIFF t ∈ subsets r
   
   [semiring_def]  Definition
      
      ⊢ ∀r. semiring r ⇔
            subset_class (space r) (subsets r) ∧ ∅ ∈ subsets r ∧
            (∀s t. s ∈ subsets r ∧ t ∈ subsets r ⇒ s ∩ t ∈ subsets r) ∧
            ∀s t.
              s ∈ subsets r ∧ t ∈ subsets r ⇒
              ∃c. c ⊆ subsets r ∧ FINITE c ∧ disjoint c ∧
                  s DIFF t = BIGUNION c
   
   [set_liminf_def]  Definition
      
      ⊢ ∀E. liminf E =
            BIGUNION (IMAGE (λm. BIGINTER {E n | m ≤ n}) 𝕌(:num))
   
   [set_limsup_def]  Definition
      
      ⊢ ∀E. limsup E =
            BIGINTER (IMAGE (λm. BIGUNION {E n | m ≤ n}) 𝕌(:num))
   
   [sigma_algebra_alt]  Definition
      
      ⊢ ∀sp sts.
          sigma_algebra_alt sp sts ⇔
          algebra (sp,sts) ∧
          ∀A. IMAGE A 𝕌(:num) ⊆ sts ⇒ BIGUNION {A i | i ∈ 𝕌(:num)} ∈ sts
   
   [sigma_algebra_def]  Definition
      
      ⊢ ∀a. sigma_algebra a ⇔
            algebra a ∧
            ∀c. countable c ∧ c ⊆ subsets a ⇒ BIGUNION c ∈ subsets a
   
   [sigma_def]  Definition
      
      ⊢ ∀sp sts.
          sigma sp sts = (sp,BIGINTER {s | sts ⊆ s ∧ sigma_algebra (sp,s)})
   
   [sigma_function_def]  Definition
      
      ⊢ ∀sp A f.
          sigma sp A f = (sp,IMAGE (λs. PREIMAGE f s ∩ sp) (subsets A))
   
   [sigma_functions_def]  Definition
      
      ⊢ ∀sp A f J.
          sigma sp A f J =
          sigma sp
            (BIGUNION
               (IMAGE
                  (λi. IMAGE (λs. PREIMAGE (f i) s ∩ sp) (subsets (A i))) J))
   
   [smallest_ring_def]  Definition
      
      ⊢ ∀sp sts.
          smallest_ring sp sts = (sp,BIGINTER {s | sts ⊆ s ∧ ring (sp,s)})
   
   [space_def]  Definition
      
      ⊢ ∀x y. space (x,y) = x
   
   [subset_class_def]  Definition
      
      ⊢ ∀sp sts. subset_class sp sts ⇔ ∀x. x ∈ sts ⇒ x ⊆ sp
   
   [subsets_def]  Definition
      
      ⊢ ∀x y. subsets (x,y) = y
   
   [ALGEBRA_ALT_INTER]  Theorem
      
      ⊢ ∀a. algebra a ⇔
            subset_class (space a) (subsets a) ∧ ∅ ∈ subsets a ∧
            (∀s. s ∈ subsets a ⇒ space a DIFF s ∈ subsets a) ∧
            ∀s t. s ∈ subsets a ∧ t ∈ subsets a ⇒ s ∩ t ∈ subsets a
   
   [ALGEBRA_COMPL]  Theorem
      
      ⊢ ∀a s. algebra a ∧ s ∈ subsets a ⇒ space a DIFF s ∈ subsets a
   
   [ALGEBRA_COMPL_SETS]  Theorem
      
      ⊢ ∀sp sts a. algebra (sp,sts) ∧ a ∈ sts ⇒ sp DIFF a ∈ sts
   
   [ALGEBRA_DIFF]  Theorem
      
      ⊢ ∀a s t.
          algebra a ∧ s ∈ subsets a ∧ t ∈ subsets a ⇒ s DIFF t ∈ subsets a
   
   [ALGEBRA_EMPTY]  Theorem
      
      ⊢ ∀a. algebra a ⇒ ∅ ∈ subsets a
   
   [ALGEBRA_FINITE_INTER]  Theorem
      
      ⊢ ∀a f n.
          algebra a ∧ 0 < n ∧ (∀i. i < n ⇒ f i ∈ subsets a) ⇒
          BIGINTER (IMAGE f (count n)) ∈ subsets a
   
   [ALGEBRA_FINITE_INTER']  Theorem
      
      ⊢ ∀a c.
          algebra a ∧ FINITE c ∧ c ⊆ subsets a ∧ c ≠ ∅ ⇒
          BIGINTER c ∈ subsets a
   
   [ALGEBRA_FINITE_UNION]  Theorem
      
      ⊢ ∀a c. algebra a ∧ FINITE c ∧ c ⊆ subsets a ⇒ BIGUNION c ∈ subsets a
   
   [ALGEBRA_IMP_RING]  Theorem
      
      ⊢ ∀a. algebra a ⇒ ring a
   
   [ALGEBRA_IMP_SEMIRING]  Theorem
      
      ⊢ ∀a. algebra a ⇒ semiring a
   
   [ALGEBRA_INTER]  Theorem
      
      ⊢ ∀a s t.
          algebra a ∧ s ∈ subsets a ∧ t ∈ subsets a ⇒ s ∩ t ∈ subsets a
   
   [ALGEBRA_INTER_SPACE]  Theorem
      
      ⊢ ∀a s. algebra a ∧ s ∈ subsets a ⇒ space a ∩ s = s ∧ s ∩ space a = s
   
   [ALGEBRA_RESTRICT]  Theorem
      
      ⊢ ∀sp sts a.
          algebra (sp,sts) ∧ a ∈ sts ⇒ algebra (a,IMAGE (λs. s ∩ a) sts)
   
   [ALGEBRA_RESTRICT']  Theorem
      
      ⊢ ∀sp sts a.
          algebra (sp,sts) ∧ a ⊆ sp ⇒ algebra (a,IMAGE (λs. s ∩ a) sts)
   
   [ALGEBRA_SETS_COLLECT_CONST]  Theorem
      
      ⊢ ∀sp sts P. algebra (sp,sts) ⇒ {x | x ∈ sp ∧ P} ∈ sts
   
   [ALGEBRA_SETS_COLLECT_IMP]  Theorem
      
      ⊢ ∀sp sts P Q.
          algebra (sp,sts) ∧ {x | x ∈ sp ∧ P x} ∈ sts ⇒
          {x | x ∈ sp ∧ Q x} ∈ sts ⇒
          {x | x ∈ sp ∧ (Q x ⇒ P x)} ∈ sts
   
   [ALGEBRA_SETS_COLLECT_NEG]  Theorem
      
      ⊢ ∀sp sts P.
          algebra (sp,sts) ∧ {x | x ∈ sp ∧ P x} ∈ sts ⇒
          {x | x ∈ sp ∧ ¬P x} ∈ sts
   
   [ALGEBRA_SINGLE_SET]  Theorem
      
      ⊢ ∀X S. X ⊆ S ⇒ algebra (S,{∅; X; S DIFF X; S})
   
   [ALGEBRA_SPACE]  Theorem
      
      ⊢ ∀a. algebra a ⇒ space a ∈ subsets a
   
   [ALGEBRA_UNION]  Theorem
      
      ⊢ ∀a s t.
          algebra a ∧ s ∈ subsets a ∧ t ∈ subsets a ⇒ s ∪ t ∈ subsets a
   
   [BIGINTER_OVER_INTER_L]  Theorem
      
      ⊢ ∀f s d.
          s ≠ ∅ ⇒
          BIGINTER (IMAGE f s) ∩ d = BIGINTER (IMAGE (λi. f i ∩ d) s)
   
   [BIGINTER_OVER_INTER_R]  Theorem
      
      ⊢ ∀f s d.
          s ≠ ∅ ⇒
          d ∩ BIGINTER (IMAGE f s) = BIGINTER (IMAGE (λi. d ∩ f i) s)
   
   [BIGINTER_PAIR]  Theorem
      
      ⊢ ∀s t. BIGINTER {s; t} = s ∩ t
   
   [BIGUNION_IMAGE_BIGUNION_IMAGE_UNIV]  Theorem
      
      ⊢ ∀f. BIGUNION (IMAGE (λn. BIGUNION (IMAGE (f n) 𝕌(:num))) 𝕌(:num)) =
            BIGUNION (IMAGE (UNCURRY f) 𝕌(:num # num))
   
   [BIGUNION_IMAGE_COUNT_IMP_UNIV]  Theorem
      
      ⊢ ∀f g.
          (∀n. BIGUNION (IMAGE g (count n)) = BIGUNION (IMAGE f (count n))) ⇒
          BIGUNION (IMAGE f 𝕌(:num)) = BIGUNION (IMAGE g 𝕌(:num))
   
   [BIGUNION_IMAGE_UNIV_CROSS_UNIV]  Theorem
      
      ⊢ ∀f h.
          BIJ h 𝕌(:num) (𝕌(:num) × 𝕌(:num)) ⇒
          BIGUNION (IMAGE (UNCURRY f) 𝕌(:num # num)) =
          BIGUNION (IMAGE (UNCURRY f ∘ h) 𝕌(:num))
   
   [BIGUNION_OVER_DIFF]  Theorem
      
      ⊢ ∀f s d.
          BIGUNION (IMAGE f s) DIFF d = BIGUNION (IMAGE (λi. f i DIFF d) s)
   
   [BIGUNION_OVER_INTER_L]  Theorem
      
      ⊢ ∀f s d. BIGUNION (IMAGE f s) ∩ d = BIGUNION (IMAGE (λi. f i ∩ d) s)
   
   [BIGUNION_OVER_INTER_R]  Theorem
      
      ⊢ ∀f s d. d ∩ BIGUNION (IMAGE f s) = BIGUNION (IMAGE (λi. d ∩ f i) s)
   
   [BIGUNION_disjointed]  Theorem
      
      ⊢ ∀A. BIGUNION {disjointed A i | i ∈ 𝕌(:num)} =
            BIGUNION {A i | i ∈ 𝕌(:num)}
   
   [BINARY_RANGE]  Theorem
      
      ⊢ ∀a b. IMAGE (binary a b) 𝕌(:num) = {a; b}
   
   [COMPL_BIGINTER]  Theorem
      
      ⊢ ∀c. COMPL (BIGINTER c) = BIGUNION (IMAGE COMPL c)
   
   [COMPL_BIGINTER_IMAGE]  Theorem
      
      ⊢ ∀f. COMPL (BIGINTER (IMAGE f 𝕌(:num))) =
            BIGUNION (IMAGE (COMPL ∘ f) 𝕌(:num))
   
   [COMPL_BIGUNION]  Theorem
      
      ⊢ ∀c. c ≠ ∅ ⇒ COMPL (BIGUNION c) = BIGINTER (IMAGE COMPL c)
   
   [COMPL_BIGUNION_IMAGE]  Theorem
      
      ⊢ ∀f. COMPL (BIGUNION (IMAGE f 𝕌(:num))) =
            BIGINTER (IMAGE (COMPL ∘ f) 𝕌(:num))
   
   [DIFF_INTER_PAIR]  Theorem
      
      ⊢ ∀sp x y. sp DIFF x ∩ y = sp DIFF x ∪ (sp DIFF y)
   
   [DINTER_IMP_FINITE_INTER]  Theorem
      
      ⊢ ∀sts f.
          (∀s t. s ∈ sts ∧ t ∈ sts ⇒ s ∩ t ∈ sts) ∧ f ∈ (𝕌(:num) → sts) ⇒
          ∀n. 0 < n ⇒ BIGINTER (IMAGE f (count n)) ∈ sts
   
   [DISJOINT_CROSS_L]  Theorem
      
      ⊢ ∀s t c. DISJOINT s t ⇒ DISJOINT (s × c) (t × c)
   
   [DISJOINT_CROSS_R]  Theorem
      
      ⊢ ∀s t c. DISJOINT s t ⇒ DISJOINT (c × s) (c × t)
   
   [DISJOINT_RESTRICT_L]  Theorem
      
      ⊢ ∀s t c. DISJOINT s t ⇒ DISJOINT (s ∩ c) (t ∩ c)
   
   [DISJOINT_RESTRICT_R]  Theorem
      
      ⊢ ∀s t c. DISJOINT s t ⇒ DISJOINT (c ∩ s) (c ∩ t)
   
   [DUNION_IMP_FINITE_UNION]  Theorem
      
      ⊢ ∀sts f.
          (∀s t. s ∈ sts ∧ t ∈ sts ⇒ s ∪ t ∈ sts) ⇒
          ∀n. 0 < n ∧ (∀i. i < n ⇒ f i ∈ sts) ⇒
              BIGUNION (IMAGE f (count n)) ∈ sts
   
   [DYNKIN]  Theorem
      
      ⊢ ∀sp sts.
          subset_class sp sts ⇒
          sts ⊆ subsets (dynkin sp sts) ∧ dynkin_system (dynkin sp sts) ∧
          subset_class sp (subsets (dynkin sp sts))
   
   [DYNKIN_LEMMA]  Theorem
      
      ⊢ ∀d. dynkin_system d ∧
            (∀s t. s ∈ subsets d ∧ t ∈ subsets d ⇒ s ∩ t ∈ subsets d) ⇔
            sigma_algebra d
   
   [DYNKIN_MONOTONE]  Theorem
      
      ⊢ ∀sp a b. a ⊆ b ⇒ subsets (dynkin sp a) ⊆ subsets (dynkin sp b)
   
   [DYNKIN_SMALLEST]  Theorem
      
      ⊢ ∀sp sts D.
          sts ⊆ D ∧ D ⊆ subsets (dynkin sp sts) ∧ dynkin_system (sp,D) ⇒
          D = subsets (dynkin sp sts)
   
   [DYNKIN_STABLE]  Theorem
      
      ⊢ ∀d. dynkin_system d ⇒ dynkin (space d) (subsets d) = d
   
   [DYNKIN_STABLE_LEMMA]  Theorem
      
      ⊢ ∀sp sts. dynkin_system (sp,sts) ⇒ dynkin sp sts = (sp,sts)
   
   [DYNKIN_SUBSET]  Theorem
      
      ⊢ ∀a b.
          dynkin_system b ∧ a ⊆ subsets b ⇒
          subsets (dynkin (space b) a) ⊆ subsets b
   
   [DYNKIN_SUBSET_SIGMA]  Theorem
      
      ⊢ ∀sp sts.
          subset_class sp sts ⇒
          subsets (dynkin sp sts) ⊆ subsets (sigma sp sts)
   
   [DYNKIN_SUBSET_SUBSETS]  Theorem
      
      ⊢ ∀sp a. a ⊆ subsets (dynkin sp a)
   
   [DYNKIN_SYSTEM_ALT]  Theorem
      
      ⊢ ∀d. dynkin_system d ⇔
            subset_class (space d) (subsets d) ∧ space d ∈ subsets d ∧
            (∀s. s ∈ subsets d ⇒ space d DIFF s ∈ subsets d) ∧
            (∀f. f ∈ (𝕌(:num) → subsets d) ∧ f 0 = ∅ ∧
                 (∀n. f n ⊆ f (SUC n)) ⇒
                 BIGUNION (IMAGE f 𝕌(:num)) ∈ subsets d) ∧
            ∀f. f ∈ (𝕌(:num) → subsets d) ∧
                (∀i j. i ≠ j ⇒ DISJOINT (f i) (f j)) ⇒
                BIGUNION (IMAGE f 𝕌(:num)) ∈ subsets d
   
   [DYNKIN_SYSTEM_ALT_MONO]  Theorem
      
      ⊢ ∀d. dynkin_system d ⇔
            subset_class (space d) (subsets d) ∧ space d ∈ subsets d ∧
            (∀s t.
               s ∈ subsets d ∧ t ∈ subsets d ∧ s ⊆ t ⇒ t DIFF s ∈ subsets d) ∧
            ∀f. f ∈ (𝕌(:num) → subsets d) ∧ f 0 = ∅ ∧ (∀n. f n ⊆ f (SUC n)) ⇒
                BIGUNION (IMAGE f 𝕌(:num)) ∈ subsets d
   
   [DYNKIN_SYSTEM_COMPL]  Theorem
      
      ⊢ ∀d s. dynkin_system d ∧ s ∈ subsets d ⇒ space d DIFF s ∈ subsets d
   
   [DYNKIN_SYSTEM_COUNTABLY_DUNION]  Theorem
      
      ⊢ ∀d f.
          dynkin_system d ∧ f ∈ (𝕌(:num) → subsets d) ∧
          (∀i j. i ≠ j ⇒ DISJOINT (f i) (f j)) ⇒
          BIGUNION (IMAGE f 𝕌(:num)) ∈ subsets d
   
   [DYNKIN_SYSTEM_DUNION]  Theorem
      
      ⊢ ∀d s t.
          dynkin_system d ∧ s ∈ subsets d ∧ t ∈ subsets d ∧ DISJOINT s t ⇒
          s ∪ t ∈ subsets d
   
   [DYNKIN_SYSTEM_EMPTY]  Theorem
      
      ⊢ ∀d. dynkin_system d ⇒ ∅ ∈ subsets d
   
   [DYNKIN_SYSTEM_INCREASING]  Theorem
      
      ⊢ ∀p f.
          dynkin_system p ∧ f ∈ (𝕌(:num) → subsets p) ∧ f 0 = ∅ ∧
          (∀n. f n ⊆ f (SUC n)) ⇒
          BIGUNION (IMAGE f 𝕌(:num)) ∈ subsets p
   
   [DYNKIN_SYSTEM_SPACE]  Theorem
      
      ⊢ ∀d. dynkin_system d ⇒ space d ∈ subsets d
   
   [DYNKIN_THM]  Theorem
      
      ⊢ ∀sp sts.
          subset_class sp sts ∧ (∀s t. s ∈ sts ∧ t ∈ sts ⇒ s ∩ t ∈ sts) ⇒
          dynkin sp sts = sigma sp sts
   
   [FINITE_TWO]  Theorem
      
      ⊢ ∀s t. FINITE {s; t}
   
   [GBIGUNION_IMAGE]  Theorem
      
      ⊢ ∀s p n. {s | ∃n. p s n} = BIGUNION (IMAGE (λn. {s | p s n}) 𝕌(:γ))
   
   [GEN_COMPL_BIGINTER]  Theorem
      
      ⊢ ∀sp c.
          (∀x. x ∈ c ⇒ x ⊆ sp) ⇒
          sp DIFF BIGINTER c = BIGUNION (IMAGE (λx. sp DIFF x) c)
   
   [GEN_COMPL_BIGINTER_IMAGE]  Theorem
      
      ⊢ ∀sp f.
          (∀n. f n ⊆ sp) ⇒
          sp DIFF BIGINTER (IMAGE f 𝕌(:num)) =
          BIGUNION (IMAGE (λn. sp DIFF f n) 𝕌(:num))
   
   [GEN_COMPL_BIGUNION]  Theorem
      
      ⊢ ∀sp c.
          c ≠ ∅ ∧ (∀x. x ∈ c ⇒ x ⊆ sp) ⇒
          sp DIFF BIGUNION c = BIGINTER (IMAGE (λx. sp DIFF x) c)
   
   [GEN_COMPL_BIGUNION_IMAGE]  Theorem
      
      ⊢ ∀sp f.
          (∀n. f n ⊆ sp) ⇒
          sp DIFF BIGUNION (IMAGE f 𝕌(:num)) =
          BIGINTER (IMAGE (λn. sp DIFF f n) 𝕌(:num))
   
   [GEN_COMPL_FINITE_INTER]  Theorem
      
      ⊢ ∀sp f n.
          0 < n ⇒
          sp DIFF BIGINTER (IMAGE f (count n)) =
          BIGUNION (IMAGE (λi. sp DIFF f i) (count n))
   
   [GEN_COMPL_FINITE_UNION]  Theorem
      
      ⊢ ∀sp f n.
          0 < n ⇒
          sp DIFF BIGUNION (IMAGE f (count n)) =
          BIGINTER (IMAGE (λi. sp DIFF f i) (count n))
   
   [GEN_COMPL_INTER]  Theorem
      
      ⊢ ∀sp s t. s ⊆ sp ∧ t ⊆ sp ⇒ sp DIFF s ∩ t = sp DIFF s ∪ (sp DIFF t)
   
   [GEN_COMPL_UNION]  Theorem
      
      ⊢ ∀sp s t.
          s ⊆ sp ∧ t ⊆ sp ⇒ sp DIFF (s ∪ t) = (sp DIFF s) ∩ (sp DIFF t)
   
   [GEN_DIFF_INTER]  Theorem
      
      ⊢ ∀sp s t. s ⊆ sp ∧ t ⊆ sp ⇒ s DIFF t = s ∩ (sp DIFF t)
   
   [IMAGE_SIGMA]  Theorem
      
      ⊢ ∀sp sts f.
          subset_class sp sts ∧ BIJ f sp (IMAGE f sp) ⇒
          IMAGE (IMAGE f) (subsets (sigma sp sts)) =
          subsets (sigma (IMAGE f sp) (IMAGE (IMAGE f) sts))
   
   [IMAGE_SIGMA_ALGEBRA]  Theorem
      
      ⊢ ∀sp sts f.
          sigma_algebra (sp,sts) ∧ BIJ f sp (IMAGE f sp) ⇒
          sigma_algebra (IMAGE f sp,IMAGE (IMAGE f) sts)
   
   [INCREASING_TO_DISJOINT_SETS]  Theorem
      
      ⊢ ∀f. (∀n. f n ⊆ f (SUC n)) ⇒
            ∃g. g 0 = f 0 ∧ (∀n. 0 < n ⇒ g n = f n DIFF f (PRE n)) ∧
                (∀i j. i ≠ j ⇒ DISJOINT (g i) (g j)) ∧
                BIGUNION (IMAGE f 𝕌(:num)) = BIGUNION (IMAGE g 𝕌(:num))
   
   [INCREASING_TO_DISJOINT_SETS']  Theorem
      
      ⊢ ∀f. f 0 = ∅ ∧ (∀n. f n ⊆ f (SUC n)) ⇒
            ∃g. (∀n. g n = f (SUC n) DIFF f n) ∧
                (∀i j. i ≠ j ⇒ DISJOINT (g i) (g j)) ∧
                BIGUNION (IMAGE f 𝕌(:num)) = BIGUNION (IMAGE g 𝕌(:num))
   
   [INTER_BINARY]  Theorem
      
      ⊢ ∀a b. a ∩ b = BIGINTER {binary a b i | i ∈ 𝕌(:num)}
   
   [INTER_SPACE_EQ1]  Theorem
      
      ⊢ ∀sp sts. subset_class sp sts ⇒ ∀x. x ∈ sts ⇒ sp ∩ x = x
   
   [INTER_SPACE_REDUCE]  Theorem
      
      ⊢ ∀sp sts. subset_class sp sts ⇒ ∀x. x ∈ sts ⇒ x ∩ sp = x
   
   [IN_DYNKIN]  Theorem
      
      ⊢ ∀sp a x. x ∈ a ⇒ x ∈ subsets (dynkin sp a)
   
   [IN_LIMINF]  Theorem
      
      ⊢ ∀A x. x ∈ liminf A ⇔ ∃m. ∀n. m ≤ n ⇒ x ∈ A n
   
   [IN_LIMSUP]  Theorem
      
      ⊢ ∀A x. x ∈ limsup A ⇔ ∃N. INFINITE N ∧ ∀n. n ∈ N ⇒ x ∈ A n
   
   [IN_MEASURABLE]  Theorem
      
      ⊢ ∀a b f.
          f ∈ measurable a b ⇔
          f ∈ (space a → space b) ∧
          ∀s. s ∈ subsets b ⇒ PREIMAGE f s ∩ space a ∈ subsets a
   
   [IN_MEASURABLE_COMP]  Theorem
      
      ⊢ ∀f g h a b c.
          f ∈ measurable a b ∧ g ∈ measurable b c ∧
          (∀x. x ∈ space a ⇒ h x = g (f x)) ⇒
          h ∈ measurable a c
   
   [IN_MEASURABLE_CONG]  Theorem
      
      ⊢ ∀a b c d f g.
          a = c ∧ b = d ∧ (∀x. x ∈ space c ⇒ f x = g x) ⇒
          (f ∈ measurable a b ⇔ g ∈ measurable c d)
   
   [IN_MEASURABLE_EQ]  Theorem
      
      ⊢ ∀a b f g.
          f ∈ measurable a b ∧ (∀x. x ∈ space a ⇒ g x = f x) ⇒
          g ∈ measurable a b
   
   [IN_MEASURABLE_PROD_SIGMA]  Theorem
      
      ⊢ ∀a bx by fx fy f.
          sigma_algebra a ∧ subset_class (space bx) (subsets bx) ∧
          subset_class (space by) (subsets by) ∧ fx ∈ measurable a bx ∧
          fy ∈ measurable a by ∧ (∀z. z ∈ space a ⇒ f z = (fx z,fy z)) ⇒
          f ∈ measurable a (bx × by)
   
   [IN_PROD_SETS]  Theorem
      
      ⊢ ∀s a b. s ∈ prod_sets a b ⇔ ∃t u. s = t × u ∧ t ∈ a ∧ u ∈ b
   
   [IN_SIGMA]  Theorem
      
      ⊢ ∀sp a x. x ∈ a ⇒ x ∈ subsets (sigma sp a)
   
   [IN_SPACE_PROD_SIGMA]  Theorem
      
      ⊢ ∀a b z. z ∈ space (a × b) ⇔ FST z ∈ space a ∧ SND z ∈ space b
   
   [LIMSUP_COMPL]  Theorem
      
      ⊢ ∀E. COMPL (liminf E) = limsup (COMPL ∘ E)
   
   [LIMSUP_DIFF]  Theorem
      
      ⊢ ∀sp E. (∀n. E n ⊆ sp) ⇒ sp DIFF liminf E = limsup (λn. sp DIFF E n)
   
   [LIMSUP_MONO_STRONG]  Theorem
      
      ⊢ ∀A B. (∀y n. y ∈ A n ⇒ ∃m. n ≤ m ∧ y ∈ B m) ⇒ limsup A ⊆ limsup B
   
   [LIMSUP_MONO_STRONGER]  Theorem
      
      ⊢ ∀A B.
          (∃d. ∀y n. y ∈ A n ⇒ ∃m. n − d ≤ m ∧ y ∈ B m) ⇒
          limsup A ⊆ limsup B
   
   [LIMSUP_MONO_WEAK]  Theorem
      
      ⊢ ∀A B. (∀n. A n ⊆ B n) ⇒ limsup A ⊆ limsup B
   
   [MEASUBABLE_BIGUNION_LEMMA]  Theorem
      
      ⊢ ∀a b f.
          sigma_algebra a ∧ sigma_algebra b ∧ f ∈ (space a → space b) ∧
          (∀s. s ∈ subsets b ⇒ PREIMAGE f s ∈ subsets a) ⇒
          ∀c. countable c ∧ c ⊆ IMAGE (PREIMAGE f) (subsets b) ⇒
              BIGUNION c ∈ IMAGE (PREIMAGE f) (subsets b)
   
   [MEASURABLE_BIGUNION_PROPERTY]  Theorem
      
      ⊢ ∀a b f.
          sigma_algebra a ∧ sigma_algebra b ∧ f ∈ (space a → space b) ∧
          (∀s. s ∈ subsets b ⇒ PREIMAGE f s ∈ subsets a) ⇒
          ∀c. c ⊆ subsets b ⇒
              PREIMAGE f (BIGUNION c) = BIGUNION (IMAGE (PREIMAGE f) c)
   
   [MEASURABLE_COMP]  Theorem
      
      ⊢ ∀f g a b c.
          f ∈ measurable a b ∧ g ∈ measurable b c ⇒ g ∘ f ∈ measurable a c
   
   [MEASURABLE_COMP_STRONG]  Theorem
      
      ⊢ ∀f g a b c.
          f ∈ measurable a b ∧ sigma_algebra c ∧ g ∈ (space b → space c) ∧
          (∀x. x ∈ subsets c ⇒ PREIMAGE g x ∩ IMAGE f (space a) ∈ subsets b) ⇒
          g ∘ f ∈ measurable a c
   
   [MEASURABLE_COMP_STRONGER]  Theorem
      
      ⊢ ∀f g a b c t.
          f ∈ measurable a b ∧ sigma_algebra c ∧ g ∈ (space b → space c) ∧
          IMAGE f (space a) ⊆ t ∧
          (∀s. s ∈ subsets c ⇒ PREIMAGE g s ∩ t ∈ subsets b) ⇒
          g ∘ f ∈ measurable a c
   
   [MEASURABLE_DIFF_PROPERTY]  Theorem
      
      ⊢ ∀a b f.
          sigma_algebra a ∧ sigma_algebra b ∧ f ∈ (space a → space b) ∧
          (∀s. s ∈ subsets b ⇒ PREIMAGE f s ∈ subsets a) ⇒
          ∀s. s ∈ subsets b ⇒
              PREIMAGE f (space b DIFF s) = space a DIFF PREIMAGE f s
   
   [MEASURABLE_FST]  Theorem
      
      ⊢ ∀a b.
          sigma_algebra a ∧ sigma_algebra b ⇒ FST ∈ measurable (a × b) a
   
   [MEASURABLE_I]  Theorem
      
      ⊢ ∀a. sigma_algebra a ⇒ I ∈ measurable a a
   
   [MEASURABLE_LEMMA]  Theorem
      
      ⊢ ∀f a b sp sts.
          sigma_algebra a ∧ subset_class sp sts ∧ f ∈ (space a → sp) ∧
          b = sigma sp sts ⇒
          ((∀s. s ∈ subsets b ⇒ PREIMAGE f s ∩ space a ∈ subsets a) ⇔
           ∀s. s ∈ sts ⇒ PREIMAGE f s ∩ space a ∈ subsets a)
   
   [MEASURABLE_LIFT]  Theorem
      
      ⊢ ∀f a b.
          sigma_algebra a ∧ subset_class (space b) (subsets b) ∧
          f ∈ measurable a b ⇒
          f ∈ measurable a (sigma (space b) (subsets b))
   
   [MEASURABLE_PAIR]  Theorem
      
      ⊢ ∀a b1 b2 X Y.
          sigma_algebra a ∧ sigma_algebra b1 ∧ sigma_algebra b2 ∧
          X ∈ measurable a b1 ∧ Y ∈ measurable a b2 ⇒
          (λx. (X x,Y x)) ∈ measurable a (b1 × b2)
   
   [MEASURABLE_PROD_SIGMA]  Theorem
      
      ⊢ ∀a a1 a2 f.
          sigma_algebra a ∧ subset_class (space a1) (subsets a1) ∧
          subset_class (space a2) (subsets a2) ∧
          FST ∘ f ∈ measurable a a1 ∧ SND ∘ f ∈ measurable a a2 ⇒
          f ∈
          measurable a
            (sigma (space a1 × space a2)
               (prod_sets (subsets a1) (subsets a2)))
   
   [MEASURABLE_PROD_SIGMA']  Theorem
      
      ⊢ ∀a a1 a2 f.
          sigma_algebra a ∧ subset_class (space a1) (subsets a1) ∧
          subset_class (space a2) (subsets a2) ∧
          FST ∘ f ∈ measurable a a1 ∧ SND ∘ f ∈ measurable a a2 ⇒
          f ∈ measurable a (a1 × a2)
   
   [MEASURABLE_SIGMA]  Theorem
      
      ⊢ ∀f a b sp.
          sigma_algebra a ∧ subset_class sp b ∧ f ∈ (space a → sp) ∧
          (∀s. s ∈ b ⇒ PREIMAGE f s ∩ space a ∈ subsets a) ⇒
          f ∈ measurable a (sigma sp b)
   
   [MEASURABLE_SIGMA_PREIMAGES]  Theorem
      
      ⊢ ∀a b f.
          sigma_algebra a ∧ sigma_algebra b ∧ f ∈ (space a → space b) ∧
          (∀s. s ∈ subsets b ⇒ PREIMAGE f s ∈ subsets a) ⇒
          sigma_algebra (space a,IMAGE (PREIMAGE f) (subsets b))
   
   [MEASURABLE_SND]  Theorem
      
      ⊢ ∀a b.
          sigma_algebra a ∧ sigma_algebra b ⇒ SND ∈ measurable (a × b) b
   
   [MEASURABLE_SUBSET]  Theorem
      
      ⊢ ∀a b.
          sigma_algebra a ∧ subset_class (space b) (subsets b) ⇒
          measurable a b ⊆ measurable a (sigma (space b) (subsets b))
   
   [MEASURABLE_UP_LIFT]  Theorem
      
      ⊢ ∀sp a b c f.
          f ∈ measurable (sp,a) c ∧ sigma_algebra (sp,b) ∧ a ⊆ b ⇒
          f ∈ measurable (sp,b) c
   
   [MEASURABLE_UP_SIGMA]  Theorem
      
      ⊢ ∀a b.
          subset_class (space a) (subsets a) ∧ sigma_algebra b ⇒
          measurable a b ⊆ measurable (sigma (space a) (subsets a)) b
   
   [MEASURABLE_UP_SUBSET]  Theorem
      
      ⊢ ∀sp a b c.
          a ⊆ b ∧ sigma_algebra (sp,b) ⇒
          measurable (sp,a) c ⊆ measurable (sp,b) c
   
   [POW_ALGEBRA]  Theorem
      
      ⊢ ∀sp. algebra (sp,POW sp)
   
   [POW_SIGMA_ALGEBRA]  Theorem
      
      ⊢ ∀sp. sigma_algebra (sp,POW sp)
   
   [PREIMAGE_SIGMA]  Theorem
      
      ⊢ ∀Z sp sts f.
          subset_class sp sts ∧ f ∈ (Z → sp) ⇒
          IMAGE (λs. PREIMAGE f s ∩ Z) (subsets (sigma sp sts)) =
          subsets (sigma Z (IMAGE (λs. PREIMAGE f s ∩ Z) sts))
   
   [PREIMAGE_SIGMA_ALGEBRA]  Theorem
      
      ⊢ ∀sp A f.
          sigma_algebra A ∧ f ∈ (sp → space A) ⇒
          sigma_algebra (sp,IMAGE (λs. PREIMAGE f s ∩ sp) (subsets A))
   
   [RING_BIGUNION]  Theorem
      
      ⊢ ∀sp sts A n.
          ring (sp,sts) ∧ IMAGE A 𝕌(:num) ⊆ sts ⇒
          BIGUNION {A i | i < n} ∈ sts
   
   [RING_DIFF]  Theorem
      
      ⊢ ∀r s t.
          ring r ∧ s ∈ subsets r ∧ t ∈ subsets r ⇒ s DIFF t ∈ subsets r
   
   [RING_DIFF_ALT]  Theorem
      
      ⊢ ∀a b sp sts. ring (sp,sts) ∧ a ∈ sts ∧ b ∈ sts ⇒ a DIFF b ∈ sts
   
   [RING_EMPTY]  Theorem
      
      ⊢ ∀r. ring r ⇒ ∅ ∈ subsets r
   
   [RING_FINITE_BIGUNION1]  Theorem
      
      ⊢ ∀X sp sts. ring (sp,sts) ∧ FINITE X ⇒ X ⊆ sts ⇒ BIGUNION X ∈ sts
   
   [RING_FINITE_BIGUNION2]  Theorem
      
      ⊢ ∀A N sp sts.
          ring (sp,sts) ∧ FINITE N ∧ (∀i. i ∈ N ⇒ A i ∈ sts) ⇒
          BIGUNION {A i | i ∈ N} ∈ sts
   
   [RING_FINITE_INTER]  Theorem
      
      ⊢ ∀r f n.
          ring r ∧ 0 < n ∧ (∀i. i < n ⇒ f i ∈ subsets r) ⇒
          BIGINTER (IMAGE f (count n)) ∈ subsets r
   
   [RING_FINITE_INTER']  Theorem
      
      ⊢ ∀r c.
          ring r ∧ FINITE c ∧ c ⊆ subsets r ∧ c ≠ ∅ ⇒
          BIGINTER c ∈ subsets r
   
   [RING_FINITE_UNION]  Theorem
      
      ⊢ ∀r c. ring r ∧ c ⊆ subsets r ∧ FINITE c ⇒ BIGUNION c ∈ subsets r
   
   [RING_FINITE_UNION_ALT]  Theorem
      
      ⊢ ∀r f n.
          ring r ∧ (∀i. i < n ⇒ f i ∈ subsets r) ⇒
          BIGUNION (IMAGE f (count n)) ∈ subsets r
   
   [RING_IMP_SEMIRING]  Theorem
      
      ⊢ ∀r. ring r ⇒ semiring r
   
   [RING_INSERT]  Theorem
      
      ⊢ ∀x A sp sts. ring (sp,sts) ∧ {x} ∈ sts ∧ A ∈ sts ⇒ x INSERT A ∈ sts
   
   [RING_INTER]  Theorem
      
      ⊢ ∀r s t. ring r ∧ s ∈ subsets r ∧ t ∈ subsets r ⇒ s ∩ t ∈ subsets r
   
   [RING_SETS_COLLECT_FINITE]  Theorem
      
      ⊢ ∀sp sts s P.
          ring (sp,sts) ∧ (∀i. i ∈ s ⇒ equiv_class P sp i ∈ sts) ∧ FINITE s ⇒
          {x | x ∈ sp ∧ ∃i. i ∈ s ∧ P i x} ∈ sts
   
   [RING_SPACE_IMP_ALGEBRA]  Theorem
      
      ⊢ ∀r. ring r ∧ space r ∈ subsets r ⇒ algebra r
   
   [RING_UNION]  Theorem
      
      ⊢ ∀r s t. ring r ∧ s ∈ subsets r ∧ t ∈ subsets r ⇒ s ∪ t ∈ subsets r
   
   [SEMIRING_DIFF]  Theorem
      
      ⊢ ∀r s t.
          semiring r ∧ s ∈ subsets r ∧ t ∈ subsets r ⇒
          ∃c. c ⊆ subsets r ∧ FINITE c ∧ disjoint c ∧ s DIFF t = BIGUNION c
   
   [SEMIRING_DIFF_ALT]  Theorem
      
      ⊢ ∀r s t.
          semiring r ∧ s ∈ subsets r ∧ t ∈ subsets r ⇒
          ∃f n.
            (∀i. i < n ⇒ f i ∈ subsets r) ∧
            (∀i j. i < n ∧ j < n ∧ i ≠ j ⇒ DISJOINT (f i) (f j)) ∧
            s DIFF t = BIGUNION (IMAGE f (count n))
   
   [SEMIRING_EMPTY]  Theorem
      
      ⊢ ∀r. semiring r ⇒ ∅ ∈ subsets r
   
   [SEMIRING_FINITE_INTER]  Theorem
      
      ⊢ ∀r f n.
          semiring r ∧ 0 < n ∧ (∀i. i < n ⇒ f i ∈ subsets r) ⇒
          BIGINTER (IMAGE f (count n)) ∈ subsets r
   
   [SEMIRING_FINITE_INTER']  Theorem
      
      ⊢ ∀r c.
          semiring r ∧ FINITE c ∧ c ⊆ subsets r ∧ c ≠ ∅ ⇒
          BIGINTER c ∈ subsets r
   
   [SEMIRING_INTER]  Theorem
      
      ⊢ ∀r s t.
          semiring r ∧ s ∈ subsets r ∧ t ∈ subsets r ⇒ s ∩ t ∈ subsets r
   
   [SEMIRING_PROD_SETS]  Theorem
      
      ⊢ ∀a b.
          semiring a ∧ semiring b ⇒
          semiring (space a × space b,prod_sets (subsets a) (subsets b))
   
   [SEMIRING_PROD_SETS']  Theorem
      
      ⊢ ∀a b.
          sigma_algebra a ∧ sigma_algebra b ⇒
          semiring (space a × space b,prod_sets (subsets a) (subsets b))
   
   [SEMIRING_SETS_COLLECT]  Theorem
      
      ⊢ ∀sp sts P Q.
          semiring (sp,sts) ∧ {x | x ∈ sp ∧ P x} ∈ sts ∧
          {x | x ∈ sp ∧ Q x} ∈ sts ⇒
          {x | x ∈ sp ∧ P x ∧ Q x} ∈ sts
   
   [SETS_TO_DISJOINT_SETS]  Theorem
      
      ⊢ ∀sp sts f.
          (∀s. s ∈ sts ⇒ s ⊆ sp) ∧ (∀n. f n ∈ sts) ⇒
          ∃g. g 0 = f 0 ∧
              (∀n. 0 < n ⇒
                   g n = f n ∩ BIGINTER (IMAGE (λi. sp DIFF f i) (count n))) ∧
              (∀i j. i ≠ j ⇒ DISJOINT (g i) (g j)) ∧
              BIGUNION (IMAGE f 𝕌(:num)) = BIGUNION (IMAGE g 𝕌(:num))
   
   [SETS_TO_DISJOINT_SETS']  Theorem
      
      ⊢ ∀f. ∃g.
          g 0 = f 0 ∧
          (∀n. 0 < n ⇒ g n = f n ∩ BIGINTER (IMAGE (COMPL ∘ f) (count n))) ∧
          (∀i j. i ≠ j ⇒ DISJOINT (g i) (g j)) ∧
          BIGUNION (IMAGE f 𝕌(:num)) = BIGUNION (IMAGE g 𝕌(:num))
   
   [SETS_TO_INCREASING_SETS]  Theorem
      
      ⊢ ∀f. ∃g.
          g 0 = f 0 ∧ (∀n. g n = BIGUNION (IMAGE f (count1 n))) ∧
          (∀n. g n ⊆ g (SUC n)) ∧
          BIGUNION (IMAGE f 𝕌(:num)) = BIGUNION (IMAGE g 𝕌(:num))
   
   [SETS_TO_INCREASING_SETS']  Theorem
      
      ⊢ ∀f. ∃g.
          g 0 = ∅ ∧ (∀n. g n = BIGUNION (IMAGE f (count n))) ∧
          (∀n. g n ⊆ g (SUC n)) ∧
          BIGUNION (IMAGE f 𝕌(:num)) = BIGUNION (IMAGE g 𝕌(:num))
   
   [SIGMA_ALGEBRA]  Theorem
      
      ⊢ ∀p. sigma_algebra p ⇔
            subset_class (space p) (subsets p) ∧ ∅ ∈ subsets p ∧
            (∀s. s ∈ subsets p ⇒ space p DIFF s ∈ subsets p) ∧
            ∀c. countable c ∧ c ⊆ subsets p ⇒ BIGUNION c ∈ subsets p
   
   [SIGMA_ALGEBRA_ALGEBRA]  Theorem
      
      ⊢ ∀a. sigma_algebra a ⇒ algebra a
   
   [SIGMA_ALGEBRA_ALT]  Theorem
      
      ⊢ ∀a. sigma_algebra a ⇔
            algebra a ∧
            ∀f. f ∈ (𝕌(:num) → subsets a) ⇒
                BIGUNION (IMAGE f 𝕌(:num)) ∈ subsets a
   
   [SIGMA_ALGEBRA_ALT_DISJOINT]  Theorem
      
      ⊢ ∀a. sigma_algebra a ⇔
            algebra a ∧
            ∀f. f ∈ (𝕌(:num) → subsets a) ∧
                (∀m n. m ≠ n ⇒ DISJOINT (f m) (f n)) ⇒
                BIGUNION (IMAGE f 𝕌(:num)) ∈ subsets a
   
   [SIGMA_ALGEBRA_ALT_MONO]  Theorem
      
      ⊢ ∀a. sigma_algebra a ⇔
            algebra a ∧
            ∀f. f ∈ (𝕌(:num) → subsets a) ∧ f 0 = ∅ ∧ (∀n. f n ⊆ f (SUC n)) ⇒
                BIGUNION (IMAGE f 𝕌(:num)) ∈ subsets a
   
   [SIGMA_ALGEBRA_ALT_SPACE]  Theorem
      
      ⊢ ∀a. sigma_algebra a ⇔
            subset_class (space a) (subsets a) ∧ space a ∈ subsets a ∧
            (∀s. s ∈ subsets a ⇒ space a DIFF s ∈ subsets a) ∧
            ∀f. f ∈ (𝕌(:num) → subsets a) ⇒
                BIGUNION (IMAGE f 𝕌(:num)) ∈ subsets a
   
   [SIGMA_ALGEBRA_COMPL]  Theorem
      
      ⊢ ∀a s. sigma_algebra a ∧ s ∈ subsets a ⇒ space a DIFF s ∈ subsets a
   
   [SIGMA_ALGEBRA_COUNTABLE_INT]  Theorem
      
      ⊢ ∀sp sts A X.
          sigma_algebra (sp,sts) ∧ IMAGE A X ⊆ sts ∧ X ≠ ∅ ⇒
          BIGINTER {A x | x ∈ X} ∈ sts
   
   [SIGMA_ALGEBRA_COUNTABLE_INT']  Theorem
      
      ⊢ ∀sp sts A X.
          sigma_algebra (sp,sts) ∧ countable X ∧ X ≠ ∅ ∧ IMAGE A X ⊆ sts ⇒
          BIGINTER {A x | x ∈ X} ∈ sts
   
   [SIGMA_ALGEBRA_COUNTABLE_UN]  Theorem
      
      ⊢ ∀sp sts A X.
          sigma_algebra (sp,sts) ∧ IMAGE A X ⊆ sts ⇒
          BIGUNION {A x | x ∈ X} ∈ sts
   
   [SIGMA_ALGEBRA_COUNTABLE_UN']  Theorem
      
      ⊢ ∀sp sts A X.
          sigma_algebra (sp,sts) ∧ IMAGE A X ⊆ sts ∧ countable X ⇒
          BIGUNION {A x | x ∈ X} ∈ sts
   
   [SIGMA_ALGEBRA_COUNTABLE_UNION]  Theorem
      
      ⊢ ∀a c.
          sigma_algebra a ∧ countable c ∧ c ⊆ subsets a ⇒
          BIGUNION c ∈ subsets a
   
   [SIGMA_ALGEBRA_DIFF]  Theorem
      
      ⊢ ∀a s t.
          sigma_algebra a ∧ s ∈ subsets a ∧ t ∈ subsets a ⇒
          s DIFF t ∈ subsets a
   
   [SIGMA_ALGEBRA_EMPTY]  Theorem
      
      ⊢ ∀a. sigma_algebra a ⇒ ∅ ∈ subsets a
   
   [SIGMA_ALGEBRA_ENUM]  Theorem
      
      ⊢ ∀a f.
          sigma_algebra a ∧ f ∈ (𝕌(:num) → subsets a) ⇒
          BIGUNION (IMAGE f 𝕌(:num)) ∈ subsets a
   
   [SIGMA_ALGEBRA_FINITE_INTER]  Theorem
      
      ⊢ ∀a f n.
          sigma_algebra a ∧ 0 < n ∧ (∀i. i < n ⇒ f i ∈ subsets a) ⇒
          BIGINTER (IMAGE f (count n)) ∈ subsets a
   
   [SIGMA_ALGEBRA_FINITE_INTER']  Theorem
      
      ⊢ ∀a c.
          sigma_algebra a ∧ FINITE c ∧ c ⊆ subsets a ∧ c ≠ ∅ ⇒
          BIGINTER c ∈ subsets a
   
   [SIGMA_ALGEBRA_FINITE_UNION]  Theorem
      
      ⊢ ∀a c.
          sigma_algebra a ∧ FINITE c ∧ c ⊆ subsets a ⇒
          BIGUNION c ∈ subsets a
   
   [SIGMA_ALGEBRA_FN]  Theorem
      
      ⊢ ∀a. sigma_algebra a ⇔
            subset_class (space a) (subsets a) ∧ ∅ ∈ subsets a ∧
            (∀s. s ∈ subsets a ⇒ space a DIFF s ∈ subsets a) ∧
            ∀f. f ∈ (𝕌(:num) → subsets a) ⇒
                BIGUNION (IMAGE f 𝕌(:num)) ∈ subsets a
   
   [SIGMA_ALGEBRA_FN_BIGINTER]  Theorem
      
      ⊢ ∀a. sigma_algebra a ⇒
            subset_class (space a) (subsets a) ∧ ∅ ∈ subsets a ∧
            (∀s. s ∈ subsets a ⇒ space a DIFF s ∈ subsets a) ∧
            ∀f. f ∈ (𝕌(:num) → subsets a) ⇒
                BIGINTER (IMAGE f 𝕌(:num)) ∈ subsets a
   
   [SIGMA_ALGEBRA_FN_DISJOINT]  Theorem
      
      ⊢ ∀a. sigma_algebra a ⇔
            subset_class (space a) (subsets a) ∧ ∅ ∈ subsets a ∧
            (∀s. s ∈ subsets a ⇒ space a DIFF s ∈ subsets a) ∧
            (∀s t. s ∈ subsets a ∧ t ∈ subsets a ⇒ s ∪ t ∈ subsets a) ∧
            ∀f. f ∈ (𝕌(:num) → subsets a) ∧
                (∀m n. m ≠ n ⇒ DISJOINT (f m) (f n)) ⇒
                BIGUNION (IMAGE f 𝕌(:num)) ∈ subsets a
   
   [SIGMA_ALGEBRA_IMP_DYNKIN_SYSTEM]  Theorem
      
      ⊢ ∀a. sigma_algebra a ⇒ dynkin_system a
   
   [SIGMA_ALGEBRA_INTER]  Theorem
      
      ⊢ ∀a s t.
          sigma_algebra a ∧ s ∈ subsets a ∧ t ∈ subsets a ⇒
          s ∩ t ∈ subsets a
   
   [SIGMA_ALGEBRA_PROD_SIGMA]  Theorem
      
      ⊢ ∀a b.
          subset_class (space a) (subsets a) ∧
          subset_class (space b) (subsets b) ⇒
          sigma_algebra (a × b)
   
   [SIGMA_ALGEBRA_PROD_SIGMA']  Theorem
      
      ⊢ ∀X Y A B.
          subset_class X A ∧ subset_class Y B ⇒
          sigma_algebra ((X,A) × (Y,B))
   
   [SIGMA_ALGEBRA_PROD_SIGMA_WEAK]  Theorem
      
      ⊢ ∀a b. sigma_algebra a ∧ sigma_algebra b ⇒ sigma_algebra (a × b)
   
   [SIGMA_ALGEBRA_RESTRICT]  Theorem
      
      ⊢ ∀sp sts a.
          sigma_algebra (sp,sts) ∧ a ∈ sts ⇒
          sigma_algebra (a,IMAGE (λs. s ∩ a) sts)
   
   [SIGMA_ALGEBRA_RESTRICT']  Theorem
      
      ⊢ ∀sp sts a.
          sigma_algebra (sp,sts) ∧ a ⊆ sp ⇒
          sigma_algebra (a,IMAGE (λs. s ∩ a) sts)
   
   [SIGMA_ALGEBRA_RESTRICT_SUBSET]  Theorem
      
      ⊢ ∀sp sts a.
          sigma_algebra (sp,sts) ∧ a ∈ sts ⇒ IMAGE (λs. s ∩ a) sts ⊆ sts
   
   [SIGMA_ALGEBRA_SIGMA]  Theorem
      
      ⊢ ∀sp sts. subset_class sp sts ⇒ sigma_algebra (sigma sp sts)
   
   [SIGMA_ALGEBRA_SIGMA_UNIV]  Theorem
      
      ⊢ ∀sts. sigma_algebra (sigma 𝕌(:α) sts)
   
   [SIGMA_ALGEBRA_SPACE]  Theorem
      
      ⊢ ∀a. sigma_algebra a ⇒ space a ∈ subsets a
   
   [SIGMA_ALGEBRA_SUBSET_SPACE]  Theorem
      
      ⊢ ∀a s. sigma_algebra a ∧ s ∈ subsets a ⇒ s ⊆ space a
   
   [SIGMA_ALGEBRA_UNION]  Theorem
      
      ⊢ ∀a s t.
          sigma_algebra a ∧ s ∈ subsets a ∧ t ∈ subsets a ⇒
          s ∪ t ∈ subsets a
   
   [SIGMA_CONG]  Theorem
      
      ⊢ ∀sp a b.
          subsets (sigma sp a) = subsets (sigma sp b) ⇒
          sigma sp a = sigma sp b
   
   [SIGMA_MEASURABLE]  Theorem
      
      ⊢ ∀sp A f.
          sigma_algebra A ∧ f ∈ (sp → space A) ⇒
          f ∈ measurable (sigma sp A f) A
   
   [SIGMA_MONOTONE]  Theorem
      
      ⊢ ∀sp a b. a ⊆ b ⇒ subsets (sigma sp a) ⊆ subsets (sigma sp b)
   
   [SIGMA_POW]  Theorem
      
      ⊢ ∀s. sigma s (POW s) = (s,POW s)
   
   [SIGMA_PROPERTY]  Theorem
      
      ⊢ ∀sp p a.
          subset_class sp p ∧ ∅ ∈ p ∧ a ⊆ p ∧
          (∀s. s ∈ p ∩ subsets (sigma sp a) ⇒ sp DIFF s ∈ p) ∧
          (∀c. countable c ∧ c ⊆ p ∩ subsets (sigma sp a) ⇒ BIGUNION c ∈ p) ⇒
          subsets (sigma sp a) ⊆ p
   
   [SIGMA_PROPERTY_ALT]  Theorem
      
      ⊢ ∀sp p a.
          subset_class sp p ∧ ∅ ∈ p ∧ a ⊆ p ∧
          (∀s. s ∈ p ∩ subsets (sigma sp a) ⇒ sp DIFF s ∈ p) ∧
          (∀f. f ∈ (𝕌(:num) → p ∩ subsets (sigma sp a)) ⇒
               BIGUNION (IMAGE f 𝕌(:num)) ∈ p) ⇒
          subsets (sigma sp a) ⊆ p
   
   [SIGMA_PROPERTY_DISJOINT]  Theorem
      
      ⊢ ∀sp p a.
          algebra (sp,a) ∧ a ⊆ p ∧
          (∀s. s ∈ p ∩ subsets (sigma sp a) ⇒ sp DIFF s ∈ p) ∧
          (∀f. f ∈ (𝕌(:num) → p ∩ subsets (sigma sp a)) ∧ f 0 = ∅ ∧
               (∀n. f n ⊆ f (SUC n)) ⇒
               BIGUNION (IMAGE f 𝕌(:num)) ∈ p) ∧
          (∀f. f ∈ (𝕌(:num) → p ∩ subsets (sigma sp a)) ∧
               (∀i j. i ≠ j ⇒ DISJOINT (f i) (f j)) ⇒
               BIGUNION (IMAGE f 𝕌(:num)) ∈ p) ⇒
          subsets (sigma sp a) ⊆ p
   
   [SIGMA_PROPERTY_DISJOINT_LEMMA]  Theorem
      
      ⊢ ∀sp a d.
          algebra (sp,a) ∧ a ⊆ d ∧ dynkin_system (sp,d) ⇒
          subsets (sigma sp a) ⊆ d
   
   [SIGMA_PROPERTY_DISJOINT_LEMMA1]  Theorem
      
      ⊢ ∀sp sts.
          algebra (sp,sts) ⇒
          ∀s t.
            s ∈ sts ∧ t ∈ subsets (dynkin sp sts) ⇒
            s ∩ t ∈ subsets (dynkin sp sts)
   
   [SIGMA_PROPERTY_DISJOINT_LEMMA2]  Theorem
      
      ⊢ ∀sp sts.
          algebra (sp,sts) ⇒
          ∀s t.
            s ∈ subsets (dynkin sp sts) ∧ t ∈ subsets (dynkin sp sts) ⇒
            s ∩ t ∈ subsets (dynkin sp sts)
   
   [SIGMA_PROPERTY_DISJOINT_WEAK]  Theorem
      
      ⊢ ∀sp p a.
          subset_class sp p ∧ ∅ ∈ p ∧ a ⊆ p ∧
          (∀s. s ∈ p ∩ subsets (sigma sp a) ⇒ sp DIFF s ∈ p) ∧
          (∀s t. s ∈ p ∧ t ∈ p ⇒ s ∪ t ∈ p) ∧
          (∀f. f ∈ (𝕌(:num) → p ∩ subsets (sigma sp a)) ∧
               (∀m n. m ≠ n ⇒ DISJOINT (f m) (f n)) ⇒
               BIGUNION (IMAGE f 𝕌(:num)) ∈ p) ⇒
          subsets (sigma sp a) ⊆ p
   
   [SIGMA_PROPERTY_DISJOINT_WEAK_ALT]  Theorem
      
      ⊢ ∀sp p a.
          algebra (sp,a) ∧ a ⊆ p ∧ subset_class sp p ∧
          (∀s. s ∈ p ⇒ sp DIFF s ∈ p) ∧
          (∀f. f ∈ (𝕌(:num) → p) ∧ f 0 = ∅ ∧ (∀n. f n ⊆ f (SUC n)) ⇒
               BIGUNION (IMAGE f 𝕌(:num)) ∈ p) ∧
          (∀f. f ∈ (𝕌(:num) → p) ∧ (∀m n. m ≠ n ⇒ DISJOINT (f m) (f n)) ⇒
               BIGUNION (IMAGE f 𝕌(:num)) ∈ p) ⇒
          subsets (sigma sp a) ⊆ p
   
   [SIGMA_PROPERTY_DYNKIN]  Theorem
      
      ⊢ ∀sp sts d.
          subset_class sp sts ∧ (∀s t. s ∈ sts ∧ t ∈ sts ⇒ s ∩ t ∈ sts) ∧
          sts ⊆ d ∧ dynkin_system (sp,d) ⇒
          subsets (sigma sp sts) ⊆ d
   
   [SIGMA_REDUCE]  Theorem
      
      ⊢ ∀sp a. (sp,subsets (sigma sp a)) = sigma sp a
   
   [SIGMA_RESTRICT]  Theorem
      
      ⊢ ∀sp sts B.
          subset_class sp sts ∧ B ⊆ sp ⇒
          sigma_algebra (B,IMAGE (λs. s ∩ B) (subsets (sigma sp sts))) ∧
          subsets (sigma B (IMAGE (λs. s ∩ B) sts)) =
          IMAGE (λs. s ∩ B) (subsets (sigma sp sts))
   
   [SIGMA_SIMULTANEOUSLY_MEASURABLE]  Theorem
      
      ⊢ ∀sp A f J.
          (∀i. i ∈ J ⇒ sigma_algebra (A i)) ∧
          (∀i. i ∈ J ⇒ f i ∈ (sp → space (A i))) ⇒
          ∀i. i ∈ J ⇒ f i ∈ measurable (sigma sp A f J) (A i)
   
   [SIGMA_SMALLEST]  Theorem
      
      ⊢ ∀sp sts A.
          sts ⊆ A ∧ A ⊆ subsets (sigma sp sts) ∧ sigma_algebra (sp,A) ⇒
          A = subsets (sigma sp sts)
   
   [SIGMA_STABLE]  Theorem
      
      ⊢ ∀a. sigma_algebra a ⇒ sigma (space a) (subsets a) = a
   
   [SIGMA_STABLE_LEMMA]  Theorem
      
      ⊢ ∀sp sts. sigma_algebra (sp,sts) ⇒ sigma sp sts = (sp,sts)
   
   [SIGMA_SUBSET]  Theorem
      
      ⊢ ∀a b.
          sigma_algebra b ∧ a ⊆ subsets b ⇒
          subsets (sigma (space b) a) ⊆ subsets b
   
   [SIGMA_SUBSET_SUBSETS]  Theorem
      
      ⊢ ∀sp a. a ⊆ subsets (sigma sp a)
   
   [SMALLEST_RING]  Theorem
      
      ⊢ ∀sp sts. subset_class sp sts ⇒ ring (smallest_ring sp sts)
   
   [SMALLEST_RING_OF_SEMIRING]  Theorem
      
      ⊢ ∀sp sts.
          semiring (sp,sts) ⇒
          subsets (smallest_ring sp sts) =
          {BIGUNION c | c ⊆ sts ∧ FINITE c ∧ disjoint c}
   
   [SMALLEST_RING_SUBSET_SUBSETS]  Theorem
      
      ⊢ ∀sp a. a ⊆ subsets (smallest_ring sp a)
   
   [SPACE]  Theorem
      
      ⊢ ∀a. (space a,subsets a) = a
   
   [SPACE_DYNKIN]  Theorem
      
      ⊢ ∀sp sts. space (dynkin sp sts) = sp
   
   [SPACE_PROD_SIGMA]  Theorem
      
      ⊢ ∀a b. space (a × b) = space a × space b
   
   [SPACE_SIGMA]  Theorem
      
      ⊢ ∀sp a. space (sigma sp a) = sp
   
   [SPACE_SMALLEST_RING]  Theorem
      
      ⊢ ∀sp sts. space (smallest_ring sp sts) = sp
   
   [SUBSET_DIFF_DISJOINT]  Theorem
      
      ⊢ ∀s1 s2 s3. s1 ⊆ s2 DIFF s3 ⇒ DISJOINT s1 s3
   
   [SUBSET_DIFF_SUBSET]  Theorem
      
      ⊢ ∀r s t. s ⊆ t ⇒ s DIFF r ⊆ t
   
   [SUBSET_INTER_SUBSET_L]  Theorem
      
      ⊢ ∀r s t. s ⊆ t ⇒ s ∩ r ⊆ t
   
   [SUBSET_INTER_SUBSET_R]  Theorem
      
      ⊢ ∀r s t. s ⊆ t ⇒ r ∩ s ⊆ t
   
   [SUBSET_MONO_DIFF]  Theorem
      
      ⊢ ∀r s t. s ⊆ t ⇒ s DIFF r ⊆ t DIFF r
   
   [SUBSET_RESTRICT_DIFF]  Theorem
      
      ⊢ ∀r s t. s ⊆ t ⇒ r DIFF t ⊆ r DIFF s
   
   [SUBSET_RESTRICT_L]  Theorem
      
      ⊢ ∀r s t. s ⊆ t ⇒ s ∩ r ⊆ t ∩ r
   
   [SUBSET_RESTRICT_R]  Theorem
      
      ⊢ ∀r s t. s ⊆ t ⇒ r ∩ s ⊆ r ∩ t
   
   [SUBSET_TWO]  Theorem
      
      ⊢ ∀N s t. N ⊆ {s; t} ∧ N ≠ ∅ ⇒ N = {s} ∨ N = {t} ∨ N = {s; t}
   
   [TRACE_SIGMA_ALGEBRA]  Theorem
      
      ⊢ ∀a E.
          sigma_algebra a ∧ E ⊆ space a ⇒
          sigma_algebra (E,{A ∩ E | A ∈ subsets a})
   
   [UNION_BINARY]  Theorem
      
      ⊢ ∀a b. a ∪ b = BIGUNION {binary a b i | i ∈ 𝕌(:num)}
   
   [UNION_TO_3_DISJOINT_UNIONS]  Theorem
      
      ⊢ ∀s t.
          s ∪ t = s DIFF t ∪ s ∩ t ∪ (t DIFF s) ∧
          disjoint {s DIFF t; s ∩ t; t DIFF s}
   
   [UNIV_SIGMA_ALGEBRA]  Theorem
      
      ⊢ sigma_algebra (𝕌(:α),𝕌(:α -> bool))
   
   [algebra_alt]  Theorem
      
      ⊢ ∀sp sts. algebra (sp,sts) ⇔ ring (sp,sts) ∧ sp ∈ sts
   
   [algebra_alt_inter]  Theorem
      
      ⊢ ∀sp sts.
          algebra (sp,sts) ⇔
          sts ⊆ POW sp ∧ ∅ ∈ sts ∧ (∀a. a ∈ sts ⇒ sp DIFF a ∈ sts) ∧
          ∀a b. a ∈ sts ∧ b ∈ sts ⇒ a ∩ b ∈ sts
   
   [algebra_alt_union]  Theorem
      
      ⊢ ∀sp sts.
          algebra (sp,sts) ⇔
          sts ⊆ POW sp ∧ ∅ ∈ sts ∧ (∀a. a ∈ sts ⇒ sp DIFF a ∈ sts) ∧
          ∀a b. a ∈ sts ∧ b ∈ sts ⇒ a ∪ b ∈ sts
   
   [algebra_finite_space_imp_sigma_algebra]  Theorem
      
      ⊢ ∀a. algebra a ∧ FINITE (space a) ⇒ sigma_algebra a
   
   [algebra_finite_subsets_imp_sigma_algebra]  Theorem
      
      ⊢ ∀a. algebra a ∧ FINITE (subsets a) ⇒ sigma_algebra a
   
   [count1_def]  Theorem
      
      ⊢ ∀n. count1 n = {m | m ≤ n}
   
   [count1_numseg]  Theorem
      
      ⊢ ∀n. count1 n = {0 .. n}
   
   [disjoint_family_def]  Theorem
      
      ⊢ ∀A. disjoint_family A ⇔ ∀i j. i ≠ j ⇒ DISJOINT (A i) (A j)
   
   [disjoint_family_disjoint]  Theorem
      
      ⊢ ∀A. disjoint_family (disjointed A)
   
   [disjoint_family_on_def]  Theorem
      
      ⊢ ∀A J.
          disjoint_family_on A J ⇔
          ∀i j. i ∈ J ∧ j ∈ J ∧ i ≠ j ⇒ DISJOINT (A i) (A j)
   
   [disjoint_family_on_iff_disjoint]  Theorem
      
      ⊢ ∀a s.
          INJ a s (IMAGE a s) ⇒
          (disjoint_family_on a s ⇔ disjoint (IMAGE a s))
   
   [disjoint_family_on_imp_disjoint]  Theorem
      
      ⊢ ∀a s. disjoint_family_on a s ⇒ disjoint (IMAGE a s)
   
   [disjointed_subset]  Theorem
      
      ⊢ ∀A n. disjointed A n ⊆ A n
   
   [finite_decomposition]  Theorem
      
      ⊢ ∀c. FINITE c ⇒
            ∃f n.
              (∀x. x < n ⇒ f x ∈ c) ∧ c = IMAGE f (count n) ∧
              ∀i j. i < n ∧ j < n ∧ i ≠ j ⇒ f i ≠ f j
   
   [finite_decomposition_simple]  Theorem
      
      ⊢ ∀c. FINITE c ⇒ ∃f n. (∀x. x < n ⇒ f x ∈ c) ∧ c = IMAGE f (count n)
   
   [finite_disjoint_decomposition]  Theorem
      
      ⊢ ∀c. FINITE c ∧ disjoint c ⇒
            ∃f n.
              (∀i. i < n ⇒ f i ∈ c) ∧ c = IMAGE f (count n) ∧
              (∀i j. i < n ∧ j < n ∧ i ≠ j ⇒ f i ≠ f j) ∧
              ∀i j. i < n ∧ j < n ∧ i ≠ j ⇒ DISJOINT (f i) (f j)
   
   [finite_disjoint_decomposition']  Theorem
      
      ⊢ ∀c. FINITE c ∧ disjoint c ⇒
            ∃f n.
              (∀i. i < n ⇒ f i ∈ c) ∧ (∀i. n ≤ i ⇒ f i = ∅) ∧
              c = IMAGE f (count n) ∧
              BIGUNION c = BIGUNION (IMAGE f 𝕌(:num)) ∧
              (∀i j. i < n ∧ j < n ∧ i ≠ j ⇒ f i ≠ f j) ∧
              ∀i j. i < n ∧ j < n ∧ i ≠ j ⇒ DISJOINT (f i) (f j)
   
   [finite_enumeration_of_sets_has_max_non_empty]  Theorem
      
      ⊢ ∀f s.
          FINITE s ∧ (∀x. f x ∈ s) ∧ (∀m n. m ≠ n ⇒ DISJOINT (f m) (f n)) ⇒
          ∃N. ∀n. n ≥ N ⇒ f n = ∅
   
   [infinitely_often_lemma]  Theorem
      
      ⊢ ∀P. ¬(∃N. INFINITE N ∧ ∀n. n ∈ N ⇒ P n) ⇔ ∃m. ∀n. m ≤ n ⇒ ¬P n
   
   [infinity_bound_lemma]  Theorem
      
      ⊢ ∀N m. INFINITE N ⇒ ∃n. m ≤ n ∧ n ∈ N
   
   [prod_sigma_alt_sigma_functions]  Theorem
      
      ⊢ ∀A B.
          sigma_algebra A ∧ sigma_algebra B ⇒
          A × B =
          sigma (space A × space B) (binary A B) (binary FST SND) {0; 1}
   
   [prod_sigma_alt_sigma_functions']  Theorem
      
      ⊢ ∀A B.
          algebra A ∧ algebra B ⇒
          A × B =
          sigma (space A × space B) (binary A B) (binary FST SND) {0; 1}
   
   [restrict_algebra_SUBSET]  Theorem
      
      ⊢ ∀A sp.
          sigma_algebra A ∧ sp ∈ subsets A ⇒
          subsets (restrict_algebra A sp) ⊆ subsets A
   
   [restrict_algebra_reduce]  Theorem
      
      ⊢ ∀A. subset_class (space A) (subsets A) ⇒
            restrict_algebra A (space A) = A
   
   [restrict_algebra_reduce']  Theorem
      
      ⊢ ∀A. sigma_algebra A ⇒ restrict_algebra A (space A) = A
   
   [ring_alt]  Theorem
      
      ⊢ ∀sp sts.
          ring (sp,sts) ⇔
          subset_class sp sts ∧ ∅ ∈ sts ∧
          (∀s t. s ∈ sts ∧ t ∈ sts ⇒ s ∪ t ∈ sts) ∧
          ∀s t. s ∈ sts ∧ t ∈ sts ⇒ s DIFF t ∈ sts
   
   [ring_alt_pow]  Theorem
      
      ⊢ ∀sp sts.
          ring (sp,sts) ⇔
          sts ⊆ POW sp ∧ ∅ ∈ sts ∧
          (∀s t. s ∈ sts ∧ t ∈ sts ⇒ s ∪ t ∈ sts) ∧
          ∀s t. s ∈ sts ∧ t ∈ sts ⇒ s DIFF t ∈ sts
   
   [ring_alt_pow_imp]  Theorem
      
      ⊢ ∀sp sts.
          sts ⊆ POW sp ∧ ∅ ∈ sts ∧
          (∀a b. a ∈ sts ∧ b ∈ sts ⇒ a ∪ b ∈ sts) ∧
          (∀a b. a ∈ sts ∧ b ∈ sts ⇒ a DIFF b ∈ sts) ⇒
          ring (sp,sts)
   
   [ring_and_semiring]  Theorem
      
      ⊢ ∀r. ring r ⇔
            semiring r ∧
            ∀s t. s ∈ subsets r ∧ t ∈ subsets r ⇒ s ∪ t ∈ subsets r
   
   [ring_disjointed_sets]  Theorem
      
      ⊢ ∀sp sts A.
          ring (sp,sts) ∧ IMAGE A 𝕌(:num) ⊆ sts ⇒
          IMAGE (λn. disjointed A n) 𝕌(:num) ⊆ sts
   
   [semiring_alt]  Theorem
      
      ⊢ ∀sp sts.
          semiring (sp,sts) ⇔
          subset_class sp sts ∧ ∅ ∈ sts ∧
          (∀s t. s ∈ sts ∧ t ∈ sts ⇒ s ∩ t ∈ sts) ∧
          ∀s t.
            s ∈ sts ∧ t ∈ sts ⇒
            ∃c. c ⊆ sts ∧ FINITE c ∧ disjoint c ∧ s DIFF t = BIGUNION c
   
   [set_limsup_alt]  Theorem
      
      ⊢ ∀E. limsup E =
            BIGINTER (IMAGE (λn. BIGUNION (IMAGE E (from n))) 𝕌(:num))
   
   [sigma_algebra_alt_eq]  Theorem
      
      ⊢ ∀sp sts.
          sigma_algebra (sp,sts) ⇔
          algebra (sp,sts) ∧
          ∀A. IMAGE A 𝕌(:num) ⊆ sts ⇒ BIGUNION {A i | i ∈ 𝕌(:num)} ∈ sts
   
   [sigma_algebra_alt_pow]  Theorem
      
      ⊢ ∀sp sts.
          sigma_algebra (sp,sts) ⇔
          sts ⊆ POW sp ∧ ∅ ∈ sts ∧ (∀s. s ∈ sts ⇒ sp DIFF s ∈ sts) ∧
          ∀A. IMAGE A 𝕌(:num) ⊆ sts ⇒ BIGUNION {A i | i ∈ 𝕌(:num)} ∈ sts
   
   [sigma_algebra_eq_alt]  Theorem
      
      ⊢ ∀sp sts. sigma_algebra (sp,sts) ⇔ sigma_algebra_alt sp sts
   
   [sigma_algebra_iff2]  Theorem
      
      ⊢ ∀sp sts.
          sigma_algebra (sp,sts) ⇔
          sts ⊆ POW sp ∧ ∅ ∈ sts ∧ (∀s. s ∈ sts ⇒ sp DIFF s ∈ sts) ∧
          ∀A. IMAGE A 𝕌(:num) ⊆ sts ⇒ BIGUNION {A i | i ∈ 𝕌(:num)} ∈ sts
   
   [sigma_algebra_restrict_algebra]  Theorem
      
      ⊢ ∀A sp.
          sigma_algebra A ∧ sp ∈ subsets A ⇒
          sigma_algebra (restrict_algebra A sp)
   
   [sigma_algebra_sigma_function]  Theorem
      
      ⊢ ∀sp A f.
          sigma_algebra A ∧ f ∈ (sp → space A) ⇒
          sigma_algebra (sigma sp A f)
   
   [sigma_algebra_sigma_functions]  Theorem
      
      ⊢ ∀sp A f J.
          (∀i. f i ∈ (sp → space (A i))) ⇒ sigma_algebra (sigma sp A f J)
   
   [sigma_algebra_sigma_sets]  Theorem
      
      ⊢ ∀sp st. st ⊆ POW sp ⇒ sigma_algebra (sp,sigma_sets sp st)
   
   [sigma_function_alt_sigma_functions]  Theorem
      
      ⊢ ∀sp A X.
          sigma_algebra A ∧ X ∈ (sp → space A) ⇒
          sigma sp A X = sigma sp (λn. A) (λn x. X x) (count 1)
   
   [sigma_function_subset]  Theorem
      
      ⊢ ∀A B f.
          sigma_algebra A ∧ f ∈ measurable A B ⇒
          subsets (sigma (space A) B f) ⊆ subsets A
   
   [sigma_functions_1]  Theorem
      
      ⊢ ∀sp A f.
          sigma_algebra A ∧ f 0 ∈ (sp → space A) ⇒
          sigma sp (λn. A) f (count 1) = sigma sp A (f 0)
   
   [sigma_functions_subset]  Theorem
      
      ⊢ ∀A B f J.
          sigma_algebra A ∧ (∀i. i ∈ J ⇒ sigma_algebra (B i)) ∧
          (∀i. i ∈ J ⇒ f i ∈ measurable A (B i)) ⇒
          subsets (sigma (space A) B f J) ⊆ subsets A
   
   [sigma_sets_BIGINTER]  Theorem
      
      ⊢ ∀sp st A.
          st ⊆ POW sp ⇒
          (∀i. A i ∈ sigma_sets sp st) ⇒
          BIGINTER {A i | i ∈ 𝕌(:num)} ∈ sigma_sets sp st
   
   [sigma_sets_BIGINTER2]  Theorem
      
      ⊢ ∀sp st A N.
          st ⊆ POW sp ∧ (∀i. i ∈ N ⇒ A i ∈ sigma_sets sp st) ∧ N ≠ ∅ ⇒
          BIGINTER {A i | i ∈ N} ∈ sigma_sets sp st
   
   [sigma_sets_BIGUNION]  Theorem
      
      ⊢ ∀sp st A.
          (∀i. A i ∈ sigma_sets sp st) ⇒
          BIGUNION {A i | i ∈ 𝕌(:num)} ∈ sigma_sets sp st
   
   [sigma_sets_basic]  Theorem
      
      ⊢ ∀sp st a. a ∈ st ⇒ a ∈ sigma_sets sp st
   
   [sigma_sets_cases]  Theorem
      
      ⊢ ∀sp st a0.
          sigma_sets sp st a0 ⇔
          a0 = ∅ ∨ st a0 ∨ (∃a. a0 = sp DIFF a ∧ sigma_sets sp st a) ∨
          ∃A. a0 = BIGUNION {A i | i ∈ 𝕌(:num)} ∧
              ∀i. sigma_sets sp st (A i)
   
   [sigma_sets_compl]  Theorem
      
      ⊢ ∀sp st a. a ∈ sigma_sets sp st ⇒ sp DIFF a ∈ sigma_sets sp st
   
   [sigma_sets_empty]  Theorem
      
      ⊢ ∀sp st. ∅ ∈ sigma_sets sp st
   
   [sigma_sets_eq]  Theorem
      
      ⊢ ∀sp sts. sigma_algebra (sp,sts) ⇒ sigma_sets sp sts = sts
   
   [sigma_sets_fixpoint]  Theorem
      
      ⊢ ∀sp sts. sigma_algebra (sp,sts) ⇒ sigma_sets sp sts = sts
   
   [sigma_sets_ind]  Theorem
      
      ⊢ ∀sp st sigma_sets'.
          sigma_sets' ∅ ∧ (∀a. st a ⇒ sigma_sets' a) ∧
          (∀a. sigma_sets' a ⇒ sigma_sets' (sp DIFF a)) ∧
          (∀A. (∀i. sigma_sets' (A i)) ⇒
               sigma_sets' (BIGUNION {A i | i ∈ 𝕌(:num)})) ⇒
          ∀a0. sigma_sets sp st a0 ⇒ sigma_sets' a0
   
   [sigma_sets_into_sp]  Theorem
      
      ⊢ ∀sp st. st ⊆ POW sp ⇒ ∀x. x ∈ sigma_sets sp st ⇒ x ⊆ sp
   
   [sigma_sets_least_sigma_algebra]  Theorem
      
      ⊢ ∀sp A.
          A ⊆ POW sp ⇒
          sigma_sets sp A = BIGINTER {B | A ⊆ B ∧ sigma_algebra (sp,B)}
   
   [sigma_sets_rules]  Theorem
      
      ⊢ ∀sp st.
          sigma_sets sp st ∅ ∧ (∀a. st a ⇒ sigma_sets sp st a) ∧
          (∀a. sigma_sets sp st a ⇒ sigma_sets sp st (sp DIFF a)) ∧
          ∀A. (∀i. sigma_sets sp st (A i)) ⇒
              sigma_sets sp st (BIGUNION {A i | i ∈ 𝕌(:num)})
   
   [sigma_sets_sigma]  Theorem
      
      ⊢ ∀sp A. A ⊆ POW sp ⇒ sigma_sets sp A = subsets (sigma sp A)
   
   [sigma_sets_strongind]  Theorem
      
      ⊢ ∀sp st sigma_sets'.
          sigma_sets' ∅ ∧ (∀a. st a ⇒ sigma_sets' a) ∧
          (∀a. sigma_sets sp st a ∧ sigma_sets' a ⇒ sigma_sets' (sp DIFF a)) ∧
          (∀A. (∀i. sigma_sets sp st (A i) ∧ sigma_sets' (A i)) ⇒
               sigma_sets' (BIGUNION {A i | i ∈ 𝕌(:num)})) ⇒
          ∀a0. sigma_sets sp st a0 ⇒ sigma_sets' a0
   
   [sigma_sets_subset]  Theorem
      
      ⊢ ∀sp sts st.
          sigma_algebra (sp,sts) ∧ st ⊆ sts ⇒ sigma_sets sp st ⊆ sts
   
   [sigma_sets_superset_generator]  Theorem
      
      ⊢ ∀X A. A ⊆ sigma_sets X A
   
   [sigma_sets_top]  Theorem
      
      ⊢ ∀sp A. sp ∈ sigma_sets sp A
   
   [sigma_sets_union]  Theorem
      
      ⊢ ∀sp st a b.
          a ∈ sigma_sets sp st ∧ b ∈ sigma_sets sp st ⇒
          a ∪ b ∈ sigma_sets sp st
   
   [space_sigma_function]  Theorem
      
      ⊢ ∀sp A f. space (sigma sp A f) = sp
   
   [space_sigma_functions]  Theorem
      
      ⊢ ∀sp A f J. space (sigma sp A f J) = sp
   
   [subset_class_POW]  Theorem
      
      ⊢ ∀sp. subset_class sp (POW sp)
   
   [tail_countable]  Theorem
      
      ⊢ ∀A m. countable {A n | m ≤ n}
   
   [tail_not_empty]  Theorem
      
      ⊢ ∀A m. {A n | m ≤ n} ≠ ∅
   
   [trivial_algebra_of_space]  Theorem
      
      ⊢ ∀sp. algebra (sp,{∅; sp})
   
   [trivial_algebra_of_two_points]  Theorem
      
      ⊢ ∀h t. algebra ({h; t},{∅; {h}; {t}; {h; t}})
   
   [trivial_algebra_of_two_sets]  Theorem
      
      ⊢ ∀sp s. s ⊆ sp ⇒ algebra (sp,{∅; s; sp DIFF s; sp})
   
   
*)
end


Source File Identifier index Theory binding index

HOL 4, Trindemossen-2