Theorem nesym 2385

Description: Characterization of inequality in terms of reversed equality (see bicom 139). (Contributed by BJ, 7-Jul-2018.)

Assertion

Ref	Expression
nesym	|- ( A =/= B <-> -. B = A )

Proof of Theorem nesym

Step	Hyp	Ref	Expression
1		eqcom 2172	. 2 |- ( A = B <-> B = A )
2	1	necon3abii 2376	1 |- ( A =/= B <-> -. B = A )

Syntax hints:   -. wn 3   <-> wb 104   = wceq 1348   =/= wne 2340

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-in1 609  ax-in2 610  ax-5 1440  ax-gen 1442  ax-ext 2152

This theorem depends on definitions:  df-bi 116  df-cleq 2163  df-ne 2341

This theorem is referenced by:  nesymi  2386  nesymir  2387  0neqopab  5898  fzdifsuc  10037  isprm3  12072