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Mirrors > Home > ILE Home > Th. List > biid | Unicode version |
Description: Principle of identity for logical equivalence. Theorem *4.2 of [WhiteheadRussell] p. 117. (Contributed by NM, 5-Aug-1993.) |
Ref | Expression |
---|---|
biid |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | id 19 | . 2 | |
2 | 1, 1 | impbii 125 | 1 |
Colors of variables: wff set class |
Syntax hints: wb 104 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia2 106 ax-ia3 107 |
This theorem depends on definitions: df-bi 116 |
This theorem is referenced by: biidd 171 3anbi1i 1179 3anbi2i 1180 3anbi3i 1181 trubitru 1404 falbifal 1407 eqid 2164 abid2 2285 abid2f 2332 ceqsexg 2850 nnwetri 6873 exmidontriimlem3 7171 fsum2d 11363 fprod2d 11551 isstructim 12362 |
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