Proof of proveit.logic.sets.enumeration.fold theorem

see dependencies

import proveit
%proving fold

With these allowed/disallowed theorem/theory presumptions (e.g., to avoid circular dependencies), we begin our proof of
fold:
(see dependencies)

fold may now be readily provable (assuming required theorems are usable).  Simply execute "%qed".

%qed

proveit.logic.sets.enumeration.fold has been proven.

	step type	requirements	statement
0	generalization	1	⊢
1	instantiation	2, 3, 4	,  ⊢
	: , :
2	theorem		⊢
	proveit.logic.equality.lhs_via_equality
3	assumption		⊢
4	instantiation	5, 6	⊢
	:
5	axiom		⊢
	proveit.logic.sets.enumeration.enum_set_def
6	assumption		⊢