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Mirrors > Home > MPE Home > Th. List > xorexmid | Structured version Visualization version GIF version |
Description: Exclusive-or variant of the law of the excluded middle (exmid 430). This statement is ancient, going back to at least Stoic logic. This statement does not necessarily hold in intuitionistic logic. (Contributed by David A. Wheeler, 23-Feb-2019.) |
Ref | Expression |
---|---|
xorexmid | ⊢ (𝜑 ⊻ ¬ 𝜑) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | pm5.19 374 | . 2 ⊢ ¬ (𝜑 ↔ ¬ 𝜑) | |
2 | df-xor 1457 | . 2 ⊢ ((𝜑 ⊻ ¬ 𝜑) ↔ ¬ (𝜑 ↔ ¬ 𝜑)) | |
3 | 1, 2 | mpbir 220 | 1 ⊢ (𝜑 ⊻ ¬ 𝜑) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 ↔ wb 195 ⊻ wxo 1456 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 |
This theorem depends on definitions: df-bi 196 df-xor 1457 |
This theorem is referenced by: (None) |
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