%   ORIGINAL: 'h4/thm/list/LENGTH_NIL_SYM_'
% Assm: HL_TRUTH: T
% Assm: HL_FALSITY: ~F
% Assm: HL_BOOL_CASES: !t. (t <=> T) \/ (t <=> F)
% Assm: HL_EXT: !f g. (!x. f x = g x) ==> f = g
% Goal: !l. 'h4/const/num/0' = 'h4/const/list/LENGTH' l <=> l = 'h4/const/list/NIL'
%   PROCESSED
% Assm ['HL_TRUTH']: T
% Assm ['HL_FALSITY']: ~F
% Assm ['HL_BOOL_CASES']: !t. (t <=> T) \/ (t <=> F)
% Assm ['HL_EXT']: !f g. (!x. happ f x = happ g x) ==> f = g
% Goal: !l. 'h4/const/num/0' = 'h4/const/list/LENGTH' l <=> l = 'h4/const/list/NIL'
fof('HL_TRUTH', axiom, p(s(bool,'T'))).
fof('HL_FALSITY', axiom, ~ (p(s(bool,'F')))).
fof('HL_BOOL_CASES', axiom, ![T]: (s(bool,T) = s(bool,'T') | s(bool,T) = s(bool,'F'))).
fof('HL_EXT', axiom, ![V_3f4013,V_3f4009]: ![F, G]: (![X]: s(V_3f4009,happ(s(fun(V_3f4013,V_3f4009),F),s(V_3f4013,X))) = s(V_3f4009,happ(s(fun(V_3f4013,V_3f4009),G),s(V_3f4013,X))) => s(fun(V_3f4013,V_3f4009),F) = s(fun(V_3f4013,V_3f4009),G))).
fof('h4/thm/list/LENGTH_NIL_SYM_', conjecture, ![A]: ![L]: (s('h4/type/num/num','h4/const/num/0') = s('h4/type/num/num','h4/const/list/LENGTH'(s('h4/type/list/list'(A),L))) <=> s('h4/type/list/list'(A),L) = s('h4/type/list/list'(A),'h4/const/list/NIL'))).
