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Mirrors > Home > ILE Home > Th. List > pm4.53r | Unicode version |
Description: One direction of theorem *4.53 of [WhiteheadRussell] p. 120. The converse also holds in classical logic. (Contributed by Jim Kingdon, 27-Jul-2018.) |
Ref | Expression |
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pm4.53r |
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Step | Hyp | Ref | Expression |
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1 | pm4.52im 750 |
. 2
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2 | 1 | con2i 627 |
1
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Colors of variables: wff set class |
Syntax hints: ![]() ![]() ![]() ![]() |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 106 ax-ia2 107 ax-ia3 108 ax-in1 614 ax-in2 615 ax-io 709 |
This theorem depends on definitions: df-bi 117 |
This theorem is referenced by: undif3ss 3396 |
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