Theorem nesym 2465

Description: Characterization of inequality in terms of reversed equality (see bicom 140). (Contributed by BJ, 7-Jul-2018.)

Assertion

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

Proof of Theorem nesym

Step	Hyp	Ref	Expression
1		eqcom 2240	. 2 |- ( A = B <-> B = A )
2	1	necon3abii 2456	1 |- ( A =/= B <-> -. B = A )

Syntax hints:   -. wn 3   <-> wb 105   = wceq 1402   =/= wne 2420

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-in1 623  ax-in2 624  ax-5 1500  ax-gen 1502  ax-ext 2220

This theorem depends on definitions:  df-bi 117  df-cleq 2231  df-ne 2421

This theorem is referenced by:  nesymi  2466  nesymir  2467  0neqopab  6123  fzdifsuc  10466  isprm3  12874