simple-counterexamples/SimpleCounterexamples/FinitudeOfPropositions.lean
2025-04-08 22:10:20 -04:00

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-- I actually thought that ∀p, ∃q, (q ≠ p) ∧ q!
-- However, propositional extensionality tells us that (p ↔ q) → p = q
theorem finiteTrueProps
: ¬∀p, ∃q, (q ≠ p) ∧ q := by
intro h
have := h True
simp at this
theorem finiteFalseProps
: ¬∀p, ∃q, (q ≠ p) ∧ ¬q := by
intro h
have := h False
simp at this