- LAPPEND_ASSOC
-
⊢ ∀ll1 ll2 ll3. LAPPEND (LAPPEND ll1 ll2) ll3 = LAPPEND ll1 (LAPPEND ll2 ll3)
- LAPPEND_EQ_LNIL
-
⊢ (LAPPEND l1 l2 = [||]) ⇔ (l1 = [||]) ∧ (l2 = [||])
- LAPPEND_NIL_2ND
-
⊢ ∀ll. LAPPEND ll [||] = ll
- LAPPEND_fromList
-
⊢ ∀l1 l2. LAPPEND (fromList l1) (fromList l2) = fromList (l1 ++ l2)
- LAPPEND_fromSeq
-
⊢ (∀f ll. LAPPEND (fromSeq f) ll = fromSeq f) ∧
∀l f.
LAPPEND (fromList l) (fromSeq f) =
fromSeq (λn. if n < LENGTH l then EL n l else f (n − LENGTH l))
- LCONS_11
-
⊢ ∀h1 t1 h2 t2. (h1:::t1 = h2:::t2) ⇔ (h1 = h2) ∧ (t1 = t2)
- LCONS_NOT_NIL
-
⊢ ∀h t. h:::t ≠ [||] ∧ [||] ≠ h:::t
- LDROP1_THM
-
⊢ LDROP 1 = LTL
- LDROP_1
-
⊢ LDROP 1 (h:::t) = SOME t
- LDROP_ADD
-
⊢ ∀k1 k2 x.
LDROP (k1 + k2) x =
case LDROP k1 x of NONE => NONE | SOME ll => LDROP k2 ll
- LDROP_APPEND1
-
⊢ (LDROP n l1 = SOME l) ⇒ (LDROP n (LAPPEND l1 l2) = SOME (LAPPEND l l2))
- LDROP_EQ_LNIL
-
⊢ (LDROP n ll = SOME [||]) ⇔ (LLENGTH ll = SOME n)
- LDROP_FUNPOW
-
⊢ ∀n ll. LDROP n ll = FUNPOW (λm. OPTION_BIND m LTL) n (SOME ll)
- LDROP_LDROP
-
⊢ ∀ll k1 k2.
¬LFINITE ll ⇒
(THE (LDROP k2 (THE (LDROP k1 ll))) = THE (LDROP k1 (THE (LDROP k2 ll))))
- LDROP_NONE_LFINITE
-
⊢ (LDROP k l = NONE) ⇒ LFINITE l
- LDROP_SOME_LLENGTH
-
⊢ (LDROP n ll = SOME l) ∧ (LLENGTH ll = SOME m) ⇒
n ≤ m ∧ (LLENGTH l = SOME (m − n))
- LDROP_SUC
-
⊢ LDROP (SUC n) ls = OPTION_BIND (LDROP n ls) LTL
- LDROP_THM
-
⊢ (∀ll. LDROP 0 ll = SOME ll) ∧ (∀n. LDROP (SUC n) [||] = NONE) ∧
∀n h t. LDROP (SUC n) (h:::t) = LDROP n t
- LDROP_fromList
-
⊢ ∀ls n.
LDROP n (fromList ls) =
if n ≤ LENGTH ls then SOME (fromList (DROP n ls)) else NONE
- LDROP_fromSeq
-
⊢ ∀n f. LDROP n (fromSeq f) = SOME (fromSeq (f ∘ $+ n))
- LFILTER_APPEND
-
⊢ ∀P ll1 ll2.
LFINITE ll1 ⇒
(LFILTER P (LAPPEND ll1 ll2) = LAPPEND (LFILTER P ll1) (LFILTER P ll2))
- LFILTER_EQ_CONS
-
⊢ (LFILTER P ll = h:::t) ⇒
∃l ll'.
(ll = LAPPEND (fromList l) (h:::ll')) ∧ EVERY ($¬ ∘ P) l ∧ P h ∧
(LFILTER P ll' = t)
- LFILTER_EQ_NIL
-
⊢ ∀ll. (LFILTER P ll = [||]) ⇔ every ($¬ ∘ P) ll
- LFILTER_NIL
-
⊢ ∀P ll. every ($¬ ∘ P) ll ⇒ (LFILTER P ll = [||])
- LFILTER_THM
-
⊢ (∀P. LFILTER P [||] = [||]) ∧
∀P h t. LFILTER P (h:::t) = if P h then h:::LFILTER P t else LFILTER P t
- LFILTER_fromList
-
⊢ ∀p l. LFILTER p (fromList l) = fromList (FILTER p l)
- LFILTER_fromSeq
-
⊢ ∀p f.
LFILTER p (fromSeq f) =
if ∀i. ¬p (f i) then [||]
else if p (f 0) then f 0:::LFILTER p (fromSeq (f ∘ SUC))
else LFILTER p (fromSeq (f ∘ SUC))
- LFINITE
-
⊢ LFINITE ll ⇔ ∃n. LTAKE n ll = NONE
- LFINITE_APPEND
-
⊢ ∀ll1 ll2. LFINITE (LAPPEND ll1 ll2) ⇔ LFINITE ll1 ∧ LFINITE ll2
- LFINITE_DROP
-
⊢ ∀n ll. LFINITE ll ∧ n ≤ THE (LLENGTH ll) ⇒ ∃y. LDROP n ll = SOME y
- LFINITE_HAS_LENGTH
-
⊢ ∀ll. LFINITE ll ⇒ ∃n. LLENGTH ll = SOME n
- LFINITE_IMP_fromList
-
⊢ ∀ll. LFINITE ll ⇒ ∃l. ll = fromList l
- LFINITE_INDUCTION
-
⊢ ∀P. P [||] ∧ (∀h t. P t ⇒ P (h:::t)) ⇒ ∀a0. LFINITE a0 ⇒ P a0
- LFINITE_LAPPEND_IMP_NIL
-
⊢ ∀ll. LFINITE ll ⇒ ∀l2. (LAPPEND ll l2 = ll) ⇒ (l2 = [||])
- LFINITE_LFLATTEN
-
⊢ ∀lll.
every (λll. LFINITE ll ∧ ll ≠ [||]) lll ⇒
(LFINITE (LFLATTEN lll) ⇔ LFINITE lll)
- LFINITE_LGENLIST
-
⊢ LFINITE (LGENLIST f n) ⇔ n ≠ NONE
- LFINITE_LLENGTH
-
⊢ LFINITE ll ⇔ ∃n. LLENGTH ll = SOME n
- LFINITE_LNTH_NONE
-
⊢ LFINITE ll ⇔ ∃n. LNTH n ll = NONE
- LFINITE_MAP
-
⊢ ∀f ll. LFINITE (LMAP f ll) ⇔ LFINITE ll
- LFINITE_STRONG_INDUCTION
-
⊢ P [||] ∧ (∀h t. LFINITE t ∧ P t ⇒ P (h:::t)) ⇒ ∀a0. LFINITE a0 ⇒ P a0
- LFINITE_TAKE
-
⊢ ∀n ll. LFINITE ll ∧ n ≤ THE (LLENGTH ll) ⇒ ∃y. LTAKE n ll = SOME y
- LFINITE_THM
-
⊢ (LFINITE [||] ⇔ T) ∧ ∀h t. LFINITE (h:::t) ⇔ LFINITE t
- LFINITE_cases
-
⊢ ∀a0. LFINITE a0 ⇔ (a0 = [||]) ∨ ∃h t. (a0 = h:::t) ∧ LFINITE t
- LFINITE_fromList
-
⊢ ∀l. LFINITE (fromList l)
- LFINITE_fromSeq
-
⊢ ∀f. ¬LFINITE (fromSeq f)
- LFINITE_ind
-
⊢ ∀LFINITE'.
LFINITE' [||] ∧ (∀h t. LFINITE' t ⇒ LFINITE' (h:::t)) ⇒
∀a0. LFINITE a0 ⇒ LFINITE' a0
- LFINITE_rules
-
⊢ LFINITE [||] ∧ ∀h t. LFINITE t ⇒ LFINITE (h:::t)
- LFINITE_strongind
-
⊢ ∀LFINITE'.
LFINITE' [||] ∧ (∀h t. LFINITE t ∧ LFINITE' t ⇒ LFINITE' (h:::t)) ⇒
∀a0. LFINITE a0 ⇒ LFINITE' a0
- LFINITE_toList
-
⊢ ∀ll. LFINITE ll ⇒ ∃l. toList ll = SOME l
- LFINITE_toList_SOME
-
⊢ LFINITE ll ⇔ IS_SOME (toList ll)
- LFLATTEN_APPEND
-
⊢ ∀h t. LFLATTEN (h:::t) = LAPPEND h (LFLATTEN t)
- LFLATTEN_EQ_NIL
-
⊢ ∀ll. (LFLATTEN ll = [||]) ⇔ every ($= [||]) ll
- LFLATTEN_SINGLETON
-
⊢ ∀h. LFLATTEN [|h|] = h
- LFLATTEN_THM
-
⊢ (LFLATTEN [||] = [||]) ∧ (∀tl. LFLATTEN ([||]:::t) = LFLATTEN t) ∧
∀h t tl. LFLATTEN ((h:::t):::tl) = h:::LFLATTEN (t:::tl)
- LFLATTEN_fromList
-
⊢ ∀l. LFLATTEN (fromList (MAP fromList l)) = fromList (FLAT l)
- LGENLIST_CHUNK_GENLIST
-
⊢ LGENLIST f NONE =
LAPPEND (fromList (GENLIST f n)) (LGENLIST (f ∘ $+ n) NONE)
- LGENLIST_EQ_CONS
-
⊢ (LGENLIST f NONE = h:::t) ⇔ (h = f 0) ∧ (t = LGENLIST (f ∘ $+ 1) NONE)
- LGENLIST_EQ_LNIL
-
⊢ ((LGENLIST f n = [||]) ⇔ (n = SOME 0)) ∧
(([||] = LGENLIST f n) ⇔ (n = SOME 0))
- LGENLIST_EQ_fromList
-
⊢ ∀f k. LGENLIST f (SOME k) = fromList (GENLIST f k)
- LGENLIST_EQ_fromSeq
-
⊢ ∀f. LGENLIST f NONE = fromSeq f
- LGENLIST_SOME
-
⊢ (LGENLIST f (SOME 0) = [||]) ∧
∀n. LGENLIST f (SOME (SUC n)) = f 0:::LGENLIST (f ∘ SUC) (SOME n)
- LGENLIST_SOME_compute
-
⊢ (LGENLIST f (SOME 0) = [||]) ∧
(∀n. LGENLIST f (SOME (NUMERAL (BIT1 n))) =
f 0:::LGENLIST (f ∘ SUC) (SOME (NUMERAL (BIT1 n) − 1))) ∧
∀n. LGENLIST f (SOME (NUMERAL (BIT2 n))) =
f 0:::LGENLIST (f ∘ SUC) (SOME (NUMERAL (BIT1 n)))
- LHDTL_CONS_THM
-
⊢ ∀h t. (LHD (h:::t) = SOME h) ∧ (LTL (h:::t) = SOME t)
- LHDTL_EQ_SOME
-
⊢ ∀h t ll. (ll = h:::t) ⇔ (LHD ll = SOME h) ∧ (LTL ll = SOME t)
- LHD_EQ_NONE
-
⊢ ∀ll. ((LHD ll = NONE) ⇔ (ll = [||])) ∧ ((NONE = LHD ll) ⇔ (ll = [||]))
- LHD_LAPPEND
-
⊢ LHD (LAPPEND l1 l2) = if l1 = [||] then LHD l2 else LHD l1
- LHD_LCONS
-
⊢ LHD (h:::t) = SOME h
- LHD_LGENLIST
-
⊢ LHD (LGENLIST f limopt) = if limopt = SOME 0 then NONE else SOME (f 0)
- LHD_LREPEAT
-
⊢ LHD (LREPEAT l) = LHD (fromList l)
- LHD_LUNFOLD
-
⊢ LHD (LUNFOLD f x) = OPTION_MAP SND (f x)
- LHD_THM
-
⊢ (LHD [||] = NONE) ∧ ∀h t. LHD (h:::t) = SOME h
- LHD_fromList
-
⊢ LHD (fromList l) = if NULL l then NONE else SOME (HD l)
- LHD_fromSeq
-
⊢ ∀f. LHD (fromSeq f) = SOME (f 0)
- LLENGTH_0
-
⊢ (LLENGTH x = SOME 0) ⇔ (x = [||])
- LLENGTH_APPEND
-
⊢ ∀ll1 ll2.
LLENGTH (LAPPEND ll1 ll2) =
if LFINITE ll1 ∧ LFINITE ll2 then
SOME (THE (LLENGTH ll1) + THE (LLENGTH ll2))
else NONE
- LLENGTH_LGENLIST
-
⊢ ∀f. LLENGTH (LGENLIST f limopt) = limopt
- LLENGTH_LREPEAT
-
⊢ LLENGTH (LREPEAT l) = if NULL l then SOME 0 else NONE
- LLENGTH_MAP
-
⊢ ∀ll f. LLENGTH (LMAP f ll) = LLENGTH ll
- LLENGTH_THM
-
⊢ (LLENGTH [||] = SOME 0) ∧ ∀h t. LLENGTH (h:::t) = OPTION_MAP SUC (LLENGTH t)
- LLENGTH_fromList
-
⊢ ∀l. LLENGTH (fromList l) = SOME (LENGTH l)
- LLENGTH_fromSeq
-
⊢ ∀f. LLENGTH (fromSeq f) = NONE
- LLIST_BISIMULATION
-
⊢ ∀ll1 ll2.
(ll1 = ll2) ⇔
∃R. R ll1 ll2 ∧
∀ll3 ll4.
R ll3 ll4 ⇒
(ll3 = [||]) ∧ (ll4 = [||]) ∨
(LHD ll3 = LHD ll4) ∧ R (THE (LTL ll3)) (THE (LTL ll4))
- LLIST_BISIMULATION0
-
⊢ ∀ll1 ll2.
(ll1 = ll2) ⇔
∃R. R ll1 ll2 ∧
∀ll3 ll4.
R ll3 ll4 ⇒
(ll3 = [||]) ∧ (ll4 = [||]) ∨
∃h t1 t2. (ll3 = h:::t1) ∧ (ll4 = h:::t2) ∧ R t1 t2
- LLIST_BISIMULATION_I
-
⊢ ∀ll2 ll1.
(∃R. R ll1 ll2 ∧
∀ll3 ll4.
R ll3 ll4 ⇒
(ll3 = [||]) ∧ (ll4 = [||]) ∨
(LHD ll3 = LHD ll4) ∧ R (THE (LTL ll3)) (THE (LTL ll4))) ⇒
(ll1 = ll2)
- LLIST_BISIM_UPTO
-
⊢ ∀ll1 ll2 R.
R ll1 ll2 ∧
(∀ll3 ll4.
R ll3 ll4 ⇒
(ll3 = [||]) ∧ (ll4 = [||]) ∨
(LHD ll3 = LHD ll4) ∧ llist_upto R (THE (LTL ll3)) (THE (LTL ll4))) ⇒
(ll1 = ll2)
- LLIST_CASE_CONG
-
⊢ ∀M M' v f.
(M = M') ∧ ((M' = [||]) ⇒ (v = v')) ∧
(∀a0 a1. (M' = a0:::a1) ⇒ (f a0 a1 = f' a0 a1)) ⇒
(llist_CASE M v f = llist_CASE M' v' f')
- LLIST_CASE_EQ
-
⊢ (llist_CASE x v f = v') ⇔
(x = [||]) ∧ (v = v') ∨ ∃a l. (x = a:::l) ∧ (f a l = v')
- LLIST_DISTINCT
-
⊢ ∀a1 a0. [||] ≠ a0:::a1
- LLIST_EQ
-
⊢ ∀f g.
(∀x. (f x = [||]) ∧ (g x = [||]) ∨ ∃h y. (f x = h:::f y) ∧ (g x = h:::g y)) ⇒
∀x. f x = g x
- LLIST_STRONG_BISIMULATION
-
⊢ ∀ll1 ll2.
(ll1 = ll2) ⇔
∃R. R ll1 ll2 ∧
∀ll3 ll4.
R ll3 ll4 ⇒
(ll3 = ll4) ∨ ∃h t1 t2. (ll3 = h:::t1) ∧ (ll4 = h:::t2) ∧ R t1 t2
- LL_ALL_THM
-
⊢ (every P [||] ⇔ T) ∧ (every P (h:::t) ⇔ P h ∧ every P t)
- LMAP_APPEND
-
⊢ ∀f ll1 ll2. LMAP f (LAPPEND ll1 ll2) = LAPPEND (LMAP f ll1) (LMAP f ll2)
- LMAP_LGENLIST
-
⊢ LMAP f (LGENLIST g limopt) = LGENLIST (f ∘ g) limopt
- LMAP_LUNFOLD
-
⊢ ∀f g s.
LMAP f (LUNFOLD g s) = LUNFOLD (λs. OPTION_MAP (λ(x,y). (x,f y)) (g s)) s
- LMAP_MAP
-
⊢ ∀f g ll. LMAP f (LMAP g ll) = LMAP (f ∘ g) ll
- LMAP_fromList
-
⊢ LMAP f (fromList l) = fromList (MAP f l)
- LMAP_fromSeq
-
⊢ ∀f g. LMAP f (fromSeq g) = fromSeq (f ∘ g)
- LNTH_ADD
-
⊢ ∀a b ll. LNTH (a + b) ll = OPTION_BIND (LDROP a ll) (LNTH b)
- LNTH_EQ
-
⊢ ∀ll1 ll2. (ll1 = ll2) ⇔ ∀n. LNTH n ll1 = LNTH n ll2
- LNTH_HD_LDROP
-
⊢ ∀n ll. LNTH n ll = OPTION_BIND (LDROP n ll) LHD
- LNTH_LAPPEND
-
⊢ LNTH n (LAPPEND l1 l2) =
case LLENGTH l1 of
NONE => LNTH n l1
| SOME m => if n < m then LNTH n l1 else LNTH (n − m) l2
- LNTH_LDROP
-
⊢ ∀n l x. (LNTH n l = SOME x) ⇒ (LHD (THE (LDROP n l)) = SOME x)
- LNTH_LGENLIST
-
⊢ ∀n f lim.
LNTH n (LGENLIST f lim) =
case lim of
NONE => SOME (f n)
| SOME lim0 => if n < lim0 then SOME (f n) else NONE
- LNTH_LLENGTH_NONE
-
⊢ (LLENGTH l = SOME x) ∧ x ≤ n ⇒ (LNTH n l = NONE)
- LNTH_LMAP
-
⊢ ∀n f l. LNTH n (LMAP f l) = OPTION_MAP f (LNTH n l)
- LNTH_LUNFOLD
-
⊢ (LNTH 0 (LUNFOLD f x) = OPTION_MAP SND (f x)) ∧
(LNTH (SUC n) (LUNFOLD f x) =
case f x of NONE => NONE | SOME (tx,hx) => LNTH n (LUNFOLD f tx))
- LNTH_LUNFOLD_compute
-
⊢ (LNTH 0 (LUNFOLD f x) = OPTION_MAP SND (f x)) ∧
(∀n. LNTH (NUMERAL (BIT1 n)) (LUNFOLD f x) =
case f x of
NONE => NONE
| SOME (tx,hx) => LNTH (NUMERAL (BIT1 n) − 1) (LUNFOLD f tx)) ∧
∀n. LNTH (NUMERAL (BIT2 n)) (LUNFOLD f x) =
case f x of
NONE => NONE
| SOME (tx,hx) => LNTH (NUMERAL (BIT1 n)) (LUNFOLD f tx)
- LNTH_NONE_MONO
-
⊢ ∀m n l. (LNTH m l = NONE) ∧ m ≤ n ⇒ (LNTH n l = NONE)
- LNTH_THM
-
⊢ (∀n. LNTH n [||] = NONE) ∧ (∀h t. LNTH 0 (h:::t) = SOME h) ∧
∀n h t. LNTH (SUC n) (h:::t) = LNTH n t
- LNTH_fromList
-
⊢ ∀n xs. LNTH n (fromList xs) = if n < LENGTH xs then SOME (EL n xs) else NONE
- LNTH_fromSeq
-
⊢ ∀n f. LNTH n (fromSeq f) = SOME (f n)
- LNTH_rep
-
⊢ ∀i ll. LNTH i ll = llist_rep ll i
- LPREFIX_ANTISYM
-
⊢ LPREFIX l1 l2 ∧ LPREFIX l2 l1 ⇒ (l1 = l2)
- LPREFIX_APPEND
-
⊢ LPREFIX l1 l2 ⇔ ∃ll. l2 = LAPPEND l1 ll
- LPREFIX_LCONS
-
⊢ (∀ll h t. LPREFIX ll (h:::t) ⇔ (ll = [||]) ∨ ∃l. (ll = h:::l) ∧ LPREFIX l t) ∧
∀h t ll. LPREFIX (h:::t) ll ⇔ ∃l. (ll = h:::l) ∧ LPREFIX t l
- LPREFIX_LNIL
-
⊢ LPREFIX [||] ll ∧ (LPREFIX ll [||] ⇔ (ll = [||]))
- LPREFIX_LUNFOLD
-
⊢ LPREFIX ll (LUNFOLD f n) ⇔
case f n of
NONE => ll = [||]
| SOME (n,x) => ∀h t. (ll = h:::t) ⇒ (h = x) ∧ LPREFIX t (LUNFOLD f n)
- LPREFIX_NTH
-
⊢ LPREFIX l1 l2 ⇔ ∀i v. (LNTH i l1 = SOME v) ⇒ (LNTH i l2 = SOME v)
- LPREFIX_REFL
-
⊢ LPREFIX ll ll
- LPREFIX_TRANS
-
⊢ LPREFIX l1 l2 ∧ LPREFIX l2 l3 ⇒ LPREFIX l1 l3
- LPREFIX_fromList
-
⊢ ∀l ll.
LPREFIX (fromList l) ll ⇔
case toList ll of NONE => LTAKE (LENGTH l) ll = SOME l | SOME ys => l ≼ ys
- LREPEAT_EQ_LNIL
-
⊢ ((LREPEAT l = [||]) ⇔ (l = [])) ∧ (([||] = LREPEAT l) ⇔ (l = []))
- LREPEAT_NIL
-
⊢ LREPEAT [] = [||]
- LREPEAT_thm
-
⊢ LREPEAT l = LAPPEND (fromList l) (LREPEAT l)
- LSET
-
⊢ (LSET [||] = ∅) ∧ (LSET (x:::xs) = x INSERT LSET xs)
- LSUFFIX
-
⊢ (LSUFFIX l [||] ⇔ T) ∧ (LSUFFIX [||] (y:::ys) ⇔ F) ∧
(LSUFFIX (x:::xs) l ⇔ (x:::xs = l) ∨ LSUFFIX xs l)
- LSUFFIX_ANTISYM
-
⊢ ∀x y. LSUFFIX x y ∧ LSUFFIX y x ∧ LFINITE x ⇒ (x = y)
- LSUFFIX_REFL
-
⊢ ∀s. LSUFFIX s s
- LSUFFIX_TRANS
-
⊢ ∀x y z. LSUFFIX x y ∧ LSUFFIX y z ⇒ LSUFFIX x z
- LSUFFIX_fromList
-
⊢ ∀xs ys. LSUFFIX (fromList xs) (fromList ys) ⇔ IS_SUFFIX xs ys
- LTAKE_CONS_EQ_NONE
-
⊢ ∀m h t. (LTAKE m (h:::t) = NONE) ⇔ ∃n. (m = SUC n) ∧ (LTAKE n t = NONE)
- LTAKE_CONS_EQ_SOME
-
⊢ ∀m h t l.
(LTAKE m (h:::t) = SOME l) ⇔
(m = 0) ∧ (l = []) ∨
∃n l'. (m = SUC n) ∧ (LTAKE n t = SOME l') ∧ (l = h::l')
- LTAKE_DROP
-
⊢ (∀n ll.
¬LFINITE ll ⇒
(LAPPEND (fromList (THE (LTAKE n ll))) (THE (LDROP n ll)) = ll)) ∧
∀n ll.
LFINITE ll ∧ n ≤ THE (LLENGTH ll) ⇒
(LAPPEND (fromList (THE (LTAKE n ll))) (THE (LDROP n ll)) = ll)
- LTAKE_EQ
-
⊢ ∀ll1 ll2. (ll1 = ll2) ⇔ ∀n. LTAKE n ll1 = LTAKE n ll2
- LTAKE_EQ_NONE_LNTH
-
⊢ ∀n ll. (LTAKE n ll = NONE) ⇒ (LNTH n ll = NONE)
- LTAKE_EQ_SOME_CONS
-
⊢ ∀n l x. (LTAKE n l = SOME x) ⇒ ∀h. ∃y. LTAKE n (h:::l) = SOME y
- LTAKE_IMP_LDROP
-
⊢ ∀n ll l1.
(LTAKE n ll = SOME l1) ⇒
∃l2. (LDROP n ll = SOME l2) ∧ (LAPPEND (fromList l1) l2 = ll)
- LTAKE_LAPPEND1
-
⊢ ∀n l1 l2. IS_SOME (LTAKE n l1) ⇒ (LTAKE n (LAPPEND l1 l2) = LTAKE n l1)
- LTAKE_LAPPEND2
-
⊢ ∀n l1 l2.
(LTAKE n l1 = NONE) ⇒
(LTAKE n (LAPPEND l1 l2) =
OPTION_MAP ($++ (THE (toList l1))) (LTAKE (n − THE (LLENGTH l1)) l2))
- LTAKE_LAPPEND_fromList
-
⊢ ∀ll l n.
LTAKE (n + LENGTH l) (LAPPEND (fromList l) ll) =
OPTION_MAP ($++ l) (LTAKE n ll)
- LTAKE_LENGTH
-
⊢ ∀n ll l. (LTAKE n ll = SOME l) ⇒ (n = LENGTH l)
- LTAKE_LLENGTH_NONE
-
⊢ (LLENGTH ll = SOME n) ∧ n < m ⇒ (LTAKE m ll = NONE)
- LTAKE_LLENGTH_SOME
-
⊢ (LLENGTH ll = SOME n) ⇒ ∃l. (LTAKE n ll = SOME l) ∧ (toList ll = SOME l)
- LTAKE_LMAP
-
⊢ ∀n f ll. LTAKE n (LMAP f ll) = OPTION_MAP (MAP f) (LTAKE n ll)
- LTAKE_LNTH_EL
-
⊢ ∀n ll m l. (LTAKE n ll = SOME l) ∧ m < n ⇒ (LNTH m ll = SOME (EL m l))
- LTAKE_LPREFIX
-
⊢ ∀x ll. ¬LFINITE ll ⇒ ∃l. (LTAKE x ll = SOME l) ∧ LPREFIX (fromList l) ll
- LTAKE_LUNFOLD
-
⊢ (LTAKE 0 (LUNFOLD f x) = SOME []) ∧
(LTAKE (SUC n) (LUNFOLD f x) =
case f x of
NONE => NONE
| SOME (tx,hx) => OPTION_MAP (CONS hx) (LTAKE n (LUNFOLD f tx)))
- LTAKE_NIL_EQ_NONE
-
⊢ ∀m. (LTAKE m [||] = NONE) ⇔ 0 < m
- LTAKE_NIL_EQ_SOME
-
⊢ ∀l m. (LTAKE m [||] = SOME l) ⇔ (m = 0) ∧ (l = [])
- LTAKE_SNOC_LNTH
-
⊢ ∀n ll.
LTAKE (SUC n) ll =
case LTAKE n ll of
NONE => NONE
| SOME l => case LNTH n ll of NONE => NONE | SOME e => SOME (l ++ [e])
- LTAKE_TAKE_LESS
-
⊢ (LTAKE n ll = SOME l) ∧ m ≤ n ⇒ (LTAKE m ll = SOME (TAKE m l))
- LTAKE_THM
-
⊢ (∀l. LTAKE 0 l = SOME []) ∧ (∀n. LTAKE (SUC n) [||] = NONE) ∧
∀n h t. LTAKE (SUC n) (h:::t) = OPTION_MAP (CONS h) (LTAKE n t)
- LTAKE_fromList
-
⊢ ∀l. LTAKE (LENGTH l) (fromList l) = SOME l
- LTAKE_fromSeq
-
⊢ ∀n f. LTAKE n (fromSeq f) = SOME (GENLIST f n)
- LTL_EQ_NONE
-
⊢ ∀ll. ((LTL ll = NONE) ⇔ (ll = [||])) ∧ ((NONE = LTL ll) ⇔ (ll = [||]))
- LTL_HD_11
-
⊢ (LTL_HD ll1 = LTL_HD ll2) ⇒ (ll1 = ll2)
- LTL_HD_HD
-
⊢ LHD ll = OPTION_MAP SND (LTL_HD ll)
- LTL_HD_LCONS
-
⊢ LTL_HD (h:::t) = SOME (t,h)
- LTL_HD_LNIL
-
⊢ LTL_HD [||] = NONE
- LTL_HD_LTL_LHD
-
⊢ LTL_HD l = OPTION_BIND (LHD l) (λh. OPTION_BIND (LTL l) (λt. SOME (t,h)))
- LTL_HD_LUNFOLD
-
⊢ LTL_HD (LUNFOLD f x) = OPTION_MAP (LUNFOLD f ## I) (f x)
- LTL_HD_TL
-
⊢ LTL ll = OPTION_MAP FST (LTL_HD ll)
- LTL_HD_iff
-
⊢ ((LTL_HD x = SOME (t,h)) ⇔ (x = h:::t)) ∧ ((LTL_HD x = NONE) ⇔ (x = [||]))
- LTL_LAPPEND
-
⊢ LTL (LAPPEND l1 l2) =
if l1 = [||] then LTL l2 else SOME (LAPPEND (THE (LTL l1)) l2)
- LTL_LCONS
-
⊢ LTL (h:::t) = SOME t
- LTL_LGENLIST
-
⊢ LTL (LGENLIST f limopt) =
if limopt = SOME 0 then NONE
else SOME (LGENLIST (f ∘ SUC) (OPTION_MAP PRE limopt))
- LTL_LREPEAT
-
⊢ LTL (LREPEAT l) = OPTION_MAP (λt. LAPPEND t (LREPEAT l)) (LTL (fromList l))
- LTL_LUNFOLD
-
⊢ LTL (LUNFOLD f x) = OPTION_MAP (LUNFOLD f ∘ FST) (f x)
- LTL_THM
-
⊢ (LTL [||] = NONE) ∧ ∀h t. LTL (h:::t) = SOME t
- LTL_fromList
-
⊢ LTL (fromList l) = if NULL l then NONE else SOME (fromList (TL l))
- LTL_fromSeq
-
⊢ ∀f. LTL (fromSeq f) = SOME (fromSeq (f ∘ SUC))
- LUNFOLD
-
⊢ ∀f x.
LUNFOLD f x = case f x of NONE => [||] | SOME (v1,v2) => v2:::LUNFOLD f v1
- LUNFOLD_BISIMULATION
-
⊢ ∀f1 f2 x1 x2.
(LUNFOLD f1 x1 = LUNFOLD f2 x2) ⇔
∃R. R x1 x2 ∧
∀y1 y2.
R y1 y2 ⇒
(f1 y1 = NONE) ∧ (f2 y2 = NONE) ∨
∃h t1 t2. (f1 y1 = SOME (t1,h)) ∧ (f2 y2 = SOME (t2,h)) ∧ R t1 t2
- LUNFOLD_EQ
-
⊢ ∀R f s ll.
R s ll ∧
(∀s ll.
R s ll ⇒
(f s = NONE) ∧ (ll = [||]) ∨
∃s' x ll'.
(f s = SOME (s',x)) ∧ (LHD ll = SOME x) ∧ (LTL ll = SOME ll') ∧
R s' ll') ⇒
(LUNFOLD f s = ll)
- LUNFOLD_LTL_HD
-
⊢ LUNFOLD LTL_HD ll = ll
- LUNFOLD_THM
-
⊢ ∀f x v1 v2.
((f x = NONE) ⇒ (LUNFOLD f x = [||])) ∧
((f x = SOME (v1,v2)) ⇒ (LUNFOLD f x = v2:::LUNFOLD f v1))
- LUNFOLD_UNIQUE
-
⊢ ∀f g.
(∀x. g x = case f x of NONE => [||] | SOME (v1,v2) => v2:::g v1) ⇒
∀y. g y = LUNFOLD f y
- LZIP_LUNZIP
-
⊢ ∀ll. LZIP (LUNZIP ll) = ll
- MONO_every
-
⊢ (∀x. P x ⇒ Q x) ⇒ every P l ⇒ every Q l
- MONO_exists
-
⊢ (∀x. P x ⇒ Q x) ⇒ exists P l ⇒ exists Q l
- NOT_LFINITE_APPEND
-
⊢ ∀ll1 ll2. ¬LFINITE ll1 ⇒ (LAPPEND ll1 ll2 = ll1)
- NOT_LFINITE_DROP
-
⊢ ∀ll. ¬LFINITE ll ⇒ ∀n. ∃y. LDROP n ll = SOME y
- NOT_LFINITE_DROP_LFINITE
-
⊢ ∀n l t. ¬LFINITE l ∧ (LDROP n l = SOME t) ⇒ ¬LFINITE t
- NOT_LFINITE_IMP_fromSeq
-
⊢ ∀ll. ¬LFINITE ll ⇒ ∃f. ll = fromSeq f
- NOT_LFINITE_NO_LENGTH
-
⊢ ∀ll. ¬LFINITE ll ⇒ (LLENGTH ll = NONE)
- NOT_LFINITE_TAKE
-
⊢ ∀ll. ¬LFINITE ll ⇒ ∀n. ∃y. LTAKE n ll = SOME y
- always_DROP
-
⊢ ∀ll. always P ll ⇒ always P (THE (LDROP k ll))
- always_cases
-
⊢ ∀P a0. always P a0 ⇔ ∃h t. (a0 = h:::t) ∧ P (h:::t) ∧ always P t
- always_coind
-
⊢ ∀P always'.
(∀a0. always' a0 ⇒ ∃h t. (a0 = h:::t) ∧ P (h:::t) ∧ always' t) ⇒
∀a0. always' a0 ⇒ always P a0
- always_conj_l
-
⊢ ∀ll. always (λx. P x ∧ Q x) ll ⇒ always P ll
- always_eventually_ind
-
⊢ (∀ll. P ll ∨ ¬P ll ∧ Q (THE (LTL ll)) ⇒ Q ll) ⇒
∀ll. ll ≠ [||] ⇒ always (eventually P) ll ⇒ Q ll
- always_rules
-
⊢ ∀P h t. P (h:::t) ∧ always P t ⇒ always P (h:::t)
- always_thm
-
⊢ (always P [||] ⇔ F) ∧ ∀h t. always P (h:::t) ⇔ P (h:::t) ∧ always P t
- eventually_cases
-
⊢ ∀P a0. eventually P a0 ⇔ P a0 ∨ ∃h t. (a0 = h:::t) ∧ eventually P t
- eventually_ind
-
⊢ ∀P eventually'.
(∀ll. P ll ⇒ eventually' ll) ∧ (∀h t. eventually' t ⇒ eventually' (h:::t)) ⇒
∀a0. eventually P a0 ⇒ eventually' a0
- eventually_rules
-
⊢ ∀P. (∀ll. P ll ⇒ eventually P ll) ∧
∀h t. eventually P t ⇒ eventually P (h:::t)
- eventually_strongind
-
⊢ ∀P eventually'.
(∀ll. P ll ⇒ eventually' ll) ∧
(∀h t. eventually P t ∧ eventually' t ⇒ eventually' (h:::t)) ⇒
∀a0. eventually P a0 ⇒ eventually' a0
- eventually_thm
-
⊢ (eventually P [||] ⇔ P [||]) ∧
(eventually P (h:::t) ⇔ P (h:::t) ∨ eventually P t)
- eventually_until_EQN
-
⊢ eventually P = until (K T) P
- every_LAPPEND1
-
⊢ ∀P ll1 ll2. every P (LAPPEND ll1 ll2) ⇒ every P ll1
- every_LAPPEND2_LFINITE
-
⊢ ∀l P ll. LFINITE l ∧ every P (LAPPEND l ll) ⇒ every P ll
- every_LDROP
-
⊢ ∀f i ll1 ll2. every f ll1 ∧ (LDROP i ll1 = SOME ll2) ⇒ every f ll2
- every_LFILTER
-
⊢ ∀ll P. every P (LFILTER P ll)
- every_LFILTER_imp
-
⊢ ∀Q P ll. every Q ll ⇒ every Q (LFILTER P ll)
- every_LNTH
-
⊢ ∀P ll. every P ll ⇔ ∀n e. (LNTH n ll = SOME e) ⇒ P e
- every_coind
-
⊢ ∀P Q. (∀h t. Q (h:::t) ⇒ P h ∧ Q t) ⇒ ∀ll. Q ll ⇒ every P ll
- every_fromList_EVERY
-
⊢ ∀l P. every P (fromList l) ⇔ EVERY P l
- every_fromSeq
-
⊢ ∀p f. every p (fromSeq f) ⇔ ∀i. p (f i)
- every_strong_coind
-
⊢ ∀P Q.
(∀h t. Q (h:::t) ⇒ P h) ∧ (∀h t. Q (h:::t) ⇒ Q t ∨ every P t) ⇒
∀ll. Q ll ⇒ every P ll
- every_thm
-
⊢ (every P [||] ⇔ T) ∧ (every P (h:::t) ⇔ P h ∧ every P t)
- exists_LDROP
-
⊢ exists P ll ⇔ ∃n a t. (LDROP n ll = SOME (a:::t)) ∧ P a
- exists_LNTH
-
⊢ ∀l. exists P l ⇔ ∃n e. (SOME e = LNTH n l) ∧ P e
- exists_cases
-
⊢ ∀P a0.
exists P a0 ⇔ (∃h t. (a0 = h:::t) ∧ P h) ∨ ∃h t. (a0 = h:::t) ∧ exists P t
- exists_fromSeq
-
⊢ ∀p f. exists p (fromSeq f) ⇔ ∃i. p (f i)
- exists_ind
-
⊢ ∀P exists'.
(∀h t. P h ⇒ exists' (h:::t)) ∧ (∀h t. exists' t ⇒ exists' (h:::t)) ⇒
∀a0. exists P a0 ⇒ exists' a0
- exists_rules
-
⊢ ∀P. (∀h t. P h ⇒ exists P (h:::t)) ∧ ∀h t. exists P t ⇒ exists P (h:::t)
- exists_strong_ind
-
⊢ ∀P Q.
(∀h t. P h ⇒ Q (h:::t)) ∧ (∀h t. Q t ∧ exists P t ⇒ Q (h:::t)) ⇒
∀a0. exists P a0 ⇒ Q a0
- exists_strongind
-
⊢ ∀P exists'.
(∀h t. P h ⇒ exists' (h:::t)) ∧
(∀h t. exists P t ∧ exists' t ⇒ exists' (h:::t)) ⇒
∀a0. exists P a0 ⇒ exists' a0
- exists_thm
-
⊢ (exists P [||] ⇔ F) ∧ (exists P (h:::t) ⇔ P h ∨ exists P t)
- exists_thm_strong
-
⊢ exists P ll ⇔
∃n a t l.
(LDROP n ll = SOME (a:::t)) ∧ P a ∧ (LTAKE n ll = SOME l) ∧
EVERY ($¬ ∘ P) l
- fromList_11
-
⊢ ∀xs ys. (fromList xs = fromList ys) ⇔ (xs = ys)
- fromList_EQ_LNIL
-
⊢ (fromList l = [||]) ⇔ (l = [])
- fromList_NEQ_fromSeq
-
⊢ ∀l f. fromList l ≠ fromSeq f
- fromList_fromSeq
-
⊢ ∀ll. (∃l. ll = fromList l) ∨ ∃f. ll = fromSeq f
- fromSeq_11
-
⊢ ∀f g. (fromSeq f = fromSeq g) ⇔ (f = g)
- fromSeq_LCONS
-
⊢ fromSeq f = f 0:::fromSeq (f ∘ SUC)
- from_toList
-
⊢ ∀l. toList (fromList l) = SOME l
- infinite_lnth_some
-
⊢ ∀ll. ¬LFINITE ll ⇔ ∀n. ∃x. LNTH n ll = SOME x
- linear_order_to_llist
-
⊢ ∀lo X.
linear_order lo X ∧ finite_prefixes lo X ⇒
∃ll.
(X = {x | ∃i. LNTH i ll = SOME x}) ∧
lo ⊆ {(x,y) | ∃i j. i ≤ j ∧ (LNTH i ll = SOME x) ∧ (LNTH j ll = SOME y)} ∧
∀i j x. (LNTH i ll = SOME x) ∧ (LNTH j ll = SOME x) ⇒ (i = j)
- linear_order_to_llist_eq
-
⊢ ∀lo X.
linear_order lo X ∧ finite_prefixes lo X ⇒
∃ll.
(X = {x | ∃i. LNTH i ll = SOME x}) ∧
(lo =
{(x,y) | ∃i j. i ≤ j ∧ (LNTH i ll = SOME x) ∧ (LNTH j ll = SOME y)}) ∧
∀i j x. (LNTH i ll = SOME x) ∧ (LNTH j ll = SOME x) ⇒ (i = j)
- llength_rel_cases
-
⊢ ∀a0 a1.
llength_rel a0 a1 ⇔
(a0 = [||]) ∧ (a1 = 0) ∨
∃h n t. (a0 = h:::t) ∧ (a1 = SUC n) ∧ llength_rel t n
- llength_rel_ind
-
⊢ ∀llength_rel'.
llength_rel' [||] 0 ∧
(∀h n t. llength_rel' t n ⇒ llength_rel' (h:::t) (SUC n)) ⇒
∀a0 a1. llength_rel a0 a1 ⇒ llength_rel' a0 a1
- llength_rel_rules
-
⊢ llength_rel [||] 0 ∧ ∀h n t. llength_rel t n ⇒ llength_rel (h:::t) (SUC n)
- llength_rel_strongind
-
⊢ ∀llength_rel'.
llength_rel' [||] 0 ∧
(∀h n t. llength_rel t n ∧ llength_rel' t n ⇒ llength_rel' (h:::t) (SUC n)) ⇒
∀a0 a1. llength_rel a0 a1 ⇒ llength_rel' a0 a1
- llist_Axiom
-
⊢ ∀f. ∃g.
(∀x. LHD (g x) = OPTION_MAP SND (f x)) ∧
∀x. LTL (g x) = OPTION_MAP (g ∘ FST) (f x)
- llist_Axiom_1
-
⊢ ∀f. ∃g. ∀x. g x = case f x of NONE => [||] | SOME (a,b) => b:::g a
- llist_Axiom_1ue
-
⊢ ∀f. ∃!g. ∀x. g x = case f x of NONE => [||] | SOME (a,b) => b:::g a
- llist_CASES
-
⊢ ∀l. (l = [||]) ∨ ∃h t. l = h:::t
- llist_CASE_compute
-
⊢ (llist_CASE [||] b f = b) ∧ (llist_CASE (x:::ll) b f = f x ll)
- llist_forall_split
-
⊢ ∀P. (∀ll. P ll) ⇔ (∀l. P (fromList l)) ∧ ∀f. P (fromSeq f)
- llist_rep_LCONS
-
⊢ llist_rep (h:::t) = (λn. if n = 0 then SOME h else llist_rep t (n − 1))
- llist_rep_LNIL
-
⊢ llist_rep [||] = (λn. NONE)
- llist_ue_Axiom
-
⊢ ∀f. ∃!g.
(∀x. LHD (g x) = OPTION_MAP SND (f x)) ∧
∀x. LTL (g x) = OPTION_MAP (g ∘ FST) (f x)
- llist_upto_cases
-
⊢ ∀R a0 a1.
llist_upto R a0 a1 ⇔
(a1 = a0) ∨ R a0 a1 ∨ (∃y. llist_upto R a0 y ∧ llist_upto R y a1) ∨
∃x y z. (a0 = LAPPEND z x) ∧ (a1 = LAPPEND z y) ∧ llist_upto R x y
- llist_upto_context
-
⊢ ∀R x y z. llist_upto R x y ⇒ llist_upto R (LAPPEND z x) (LAPPEND z y)
- llist_upto_eq
-
⊢ ∀R x. llist_upto R x x
- llist_upto_ind
-
⊢ ∀R llist_upto'.
(∀x. llist_upto' x x) ∧ (∀x y. R x y ⇒ llist_upto' x y) ∧
(∀x y z. llist_upto' x y ∧ llist_upto' y z ⇒ llist_upto' x z) ∧
(∀x y z. llist_upto' x y ⇒ llist_upto' (LAPPEND z x) (LAPPEND z y)) ⇒
∀a0 a1. llist_upto R a0 a1 ⇒ llist_upto' a0 a1
- llist_upto_rel
-
⊢ ∀R x y. R x y ⇒ llist_upto R x y
- llist_upto_rules
-
⊢ ∀R. (∀x. llist_upto R x x) ∧ (∀x y. R x y ⇒ llist_upto R x y) ∧
(∀x y z. llist_upto R x y ∧ llist_upto R y z ⇒ llist_upto R x z) ∧
∀x y z. llist_upto R x y ⇒ llist_upto R (LAPPEND z x) (LAPPEND z y)
- llist_upto_strongind
-
⊢ ∀R llist_upto'.
(∀x. llist_upto' x x) ∧ (∀x y. R x y ⇒ llist_upto' x y) ∧
(∀x y z.
llist_upto R x y ∧ llist_upto' x y ∧ llist_upto R y z ∧ llist_upto' y z ⇒
llist_upto' x z) ∧
(∀x y z.
llist_upto R x y ∧ llist_upto' x y ⇒
llist_upto' (LAPPEND z x) (LAPPEND z y)) ⇒
∀a0 a1. llist_upto R a0 a1 ⇒ llist_upto' a0 a1
- llist_upto_trans
-
⊢ ∀R x y z. llist_upto R x y ∧ llist_upto R y z ⇒ llist_upto R x z
- lnth_fromList_some
-
⊢ ∀n l. n < LENGTH l ⇔ (LNTH n (fromList l) = SOME (EL n l))
- lnth_some_down_closed
-
⊢ ∀ll x n1 n2. (LNTH n1 ll = SOME x) ∧ n2 ≤ n1 ⇒ ∃y. LNTH n2 ll = SOME y
- lrep_ok_FUNPOW_BIND
-
⊢ lrep_ok (λn. FUNPOW (λm. OPTION_BIND m g) n fz)
- lrep_ok_MAP
-
⊢ lrep_ok (λn. OPTION_MAP f (g n)) ⇔ lrep_ok g
- lrep_ok_alt
-
⊢ lrep_ok f ⇔ ∀n. IS_SOME (f (SUC n)) ⇒ IS_SOME (f n)
- lrep_ok_cases
-
⊢ ∀a0.
lrep_ok a0 ⇔
(a0 = (λn. NONE)) ∨
∃h t. (a0 = (λn. if n = 0 then SOME h else t (n − 1))) ∧ lrep_ok t
- lrep_ok_coind
-
⊢ ∀lrep_ok'.
(∀a0.
lrep_ok' a0 ⇒
(a0 = (λn. NONE)) ∨
∃h t. (a0 = (λn. if n = 0 then SOME h else t (n − 1))) ∧ lrep_ok' t) ⇒
∀a0. lrep_ok' a0 ⇒ lrep_ok a0
- lrep_ok_rules
-
⊢ lrep_ok (λn. NONE) ∧
∀h t. lrep_ok t ⇒ lrep_ok (λn. if n = 0 then SOME h else t (n − 1))
- numopt_BISIMULATION
-
⊢ ∀mopt nopt.
(mopt = nopt) ⇔
∃R. R mopt nopt ∧
∀m n.
R m n ⇒
(m = SOME 0) ∧ (n = SOME 0) ∨
m ≠ SOME 0 ∧ n ≠ SOME 0 ∧ R (OPTION_MAP PRE m) (OPTION_MAP PRE n)
- prefixes_lprefix_total
-
⊢ ∀ll l1 l2. LPREFIX l1 ll ∧ LPREFIX l2 ll ⇒ LPREFIX l1 l2 ∨ LPREFIX l2 l1
- toList_LAPPEND_APPEND
-
⊢ (toList (LAPPEND l1 l2) = SOME x) ⇒ (x = THE (toList l1) ++ THE (toList l2))
- toList_THM
-
⊢ (toList [||] = SOME []) ∧
∀h t. toList (h:::t) = OPTION_MAP (CONS h) (toList t)
- to_fromList
-
⊢ ∀ll. LFINITE ll ⇒ (fromList (THE (toList ll)) = ll)
- until_cases
-
⊢ ∀P Q a0. until P Q a0 ⇔ Q a0 ∨ ∃h t. (a0 = h:::t) ∧ P (h:::t) ∧ until P Q t
- until_ind
-
⊢ ∀P Q until'.
(∀ll. Q ll ⇒ until' ll) ∧ (∀h t. P (h:::t) ∧ until' t ⇒ until' (h:::t)) ⇒
∀a0. until P Q a0 ⇒ until' a0
- until_rules
-
⊢ ∀P Q.
(∀ll. Q ll ⇒ until P Q ll) ∧
∀h t. P (h:::t) ∧ until P Q t ⇒ until P Q (h:::t)
- until_strongind
-
⊢ ∀P Q until'.
(∀ll. Q ll ⇒ until' ll) ∧
(∀h t. P (h:::t) ∧ until P Q t ∧ until' t ⇒ until' (h:::t)) ⇒
∀a0. until P Q a0 ⇒ until' a0