Theorem 3bitr3ri 211

Description: A chained inference from transitive law for logical equivalence. (Contributed by NM, 5-Aug-1993.)

Hypotheses

Ref	Expression
3bitr3i.1	|- ( ph <-> ps )
3bitr3i.2	|- ( ph <-> ch )
3bitr3i.3	|- ( ps <-> th )

Assertion

Ref	Expression
3bitr3ri	|- ( th <-> ch )

Proof of Theorem 3bitr3ri

Step	Hyp	Ref	Expression
1		3bitr3i.3	. 2 |- ( ps <-> th )
2		3bitr3i.1	. . 3 |- ( ph <-> ps )
3		3bitr3i.2	. . 3 |- ( ph <-> ch )
4	2, 3	bitr3i 186	. 2 |- ( ps <-> ch )
5	1, 4	bitr3i 186	1 |- ( th <-> ch )

This proof depends on syntax axioms:   <-> wb 105

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108

This proof depends on definitions:  df-bi 117

This theorem is used by:  bigolden  968  sb9  2039  sbcco  3073  dfiin2g  4045  dffun6f  5390  vtxd0nedgbfi  16540