Theorem 3bitr3rd 208

Description: Deduction from transitivity of biconditional. (Contributed by NM, 4-Aug-2006.)

Hypotheses

Ref	Expression
3bitr3d.1	|- ( ph -> ( ps <-> ch ) )
3bitr3d.2	|- ( ph -> ( ps <-> th ) )
3bitr3d.3	|- ( ph -> ( ch <-> ta ) )

Assertion

Ref	Expression
3bitr3rd	|- ( ph -> ( ta <-> th ) )

Proof of Theorem 3bitr3rd

Step	Hyp	Ref	Expression
1		3bitr3d.3	. 2 |- ( ph -> ( ch <-> ta ) )
2		3bitr3d.1	. . 3 |- ( ph -> ( ps <-> ch ) )
3		3bitr3d.2	. . 3 |- ( ph -> ( ps <-> th ) )
4	2, 3	bitr3d 179	. 2 |- ( ph -> ( ch <-> th ) )
5	1, 4	bitr3d 179	1 |- ( ph -> ( ta <-> th ) )

Syntax hints:   -> wi 4   <-> wb 98

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101

This theorem depends on definitions:  df-bi 110

This theorem is referenced by:  funconstss  5285  eqneg  7708