OR_EL_CONV : conv
STRUCTURE
listLib
SYNOPSIS
Computes by inference the result of taking the disjunction of the elements of a boolean list.
DESCRIPTION
For any object language list of the form “[x1;x2;...;xn]”, where x1, x2, ..., xn are boolean expressions, the result of evaluating 
   OR_EL_CONV “OR_EL [x1;x2;...;xn]”
is the theorem 
   |- OR_EL [x1;x2;...;xn] = b
where b is either the boolean constant that denotes the disjunction of the elements of the list, or a disjunction of those xi that are not boolean constants.
EXAMPLE
- OR_EL_CONV “OR_EL [T;F;F;T]”;
|- OR_EL [T;F;F;T] = T

- OR_EL_CONV “OR_EL [F;F;F]”;
|- OR_EL [F;F;F] = F

- OR_EL_CONV “OR_EL [F;x;y]”;
|- OR_EL [F; x; y] = x \/ y

- OR_EL_CONV “OR_EL [x;T;y]”;
|- OR_EL [x; T; y] = T

FAILURE
OR_EL_CONV tm fails if tm is not of the form described above.
HOL  Kananaskis-13