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Theorem sblbis 2072
Description: Introduce left biconditional inside of a substitution. (Contributed by NM, 19-Aug-1993.)
Hypothesis
Ref Expression
sblbis.1
Assertion
Ref Expression
sblbis

Proof of Theorem sblbis
StepHypRef Expression
1 sbbi 2071 . 2
2 sblbis.1 . . 3
32bibi2i 304 . 2
41, 3bitri 240 1
Colors of variables: wff setvar class
Syntax hints:   wb 176  wsb 1648
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1546  ax-5 1557  ax-17 1616  ax-9 1654  ax-8 1675  ax-6 1729  ax-7 1734  ax-11 1746  ax-12 1925
This theorem depends on definitions:  df-bi 177  df-an 360  df-tru 1319  df-ex 1542  df-nf 1545  df-sb 1649
This theorem is referenced by:  sb8eu  2222  sb8iota  4346
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