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Mirrors > Home > MPE Home > Th. List > Mathboxes > frege55lem1a | Structured version Visualization version Unicode version |
Description: Necessary deduction regarding substitution of value in equality. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.) |
Ref | Expression |
---|---|
frege55lem1a | if- |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | frege54cor0a 38157 | . . 3 if- | |
2 | 1 | biimpri 218 | . 2 if- |
3 | 2 | imim2i 16 | 1 if- |
Colors of variables: wff setvar class |
Syntax hints: wn 3 wi 4 wb 196 if-wif 1012 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-frege28 38124 |
This theorem depends on definitions: df-bi 197 df-or 385 df-an 386 df-ifp 1013 |
This theorem is referenced by: frege55cor1a 38163 |
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