Theorem pm5.1im 238

Description: Two propositions are equivalent if they are both true. Closed form of 2th 239. Equivalent to a bi1 186-like version of the xor-connective. This theorem stays true, no matter how you permute its operands. This is evident from its sharper version . (Contributed by Wolf Lammen, 12-May-2013.)

Assertion

Ref	Expression
pm5.1im

Proof of Theorem pm5.1im

Step	Hyp	Ref	Expression
1		ax-1 6	. 2
2		ax-1 6	. 2
3	1, 2	impbid21d 190	1

Syntax hints:  ->wi 4  <->wb 184

This theorem is referenced by:  2thd  240  pm5.501  341

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8

This theorem depends on definitions:  df-bi 185