18 lines
451 B
Plaintext
18 lines
451 B
Plaintext
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import Mathlib.Logic.Basic
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import Mathlib.Tactic.Tauto
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/-! # Common.Logic.Basic
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Additional theorems and definitions related to basic logic.
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-/
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/--
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The de Morgan law that distributes negation across a conjunction.
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-/
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theorem not_and_de_morgan {a b : Prop} : (¬(a ∧ b)) ↔ (¬ a ∨ ¬ b) := by
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tauto
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/--
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Renaming of `not_or` to indicate its relationship to de Morgan's laws.
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-/
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theorem not_or_de_morgan : ¬(p ∨ q) ↔ ¬p ∧ ¬q := not_or
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