Theorem nmotru 36463

Description: There does not exist at most one set such that ⊤ is true. (Contributed by Anthony Hart, 13-Sep-2011.)

Assertion

Ref	Expression
nmotru	⊢ ¬ ∃*𝑥⊤

Proof of Theorem nmotru

Step	Hyp	Ref	Expression
1		extru 1976	. . 3 ⊢ ∃𝑥⊤
2		neutru 36462	. . 3 ⊢ ¬ ∃!𝑥⊤
3		jcn 162	. . 3 ⊢ (∃𝑥⊤ → (¬ ∃!𝑥⊤ → ¬ (∃𝑥⊤ → ∃!𝑥⊤)))
4	1, 2, 3	mp2 9	. 2 ⊢ ¬ (∃𝑥⊤ → ∃!𝑥⊤)
5		moeu 2580	. 2 ⊢ (∃*𝑥⊤ ↔ (∃𝑥⊤ → ∃!𝑥⊤))
6	4, 5	mtbir 323	1 ⊢ ¬ ∃*𝑥⊤

Syntax hints:  ¬ wn 3   → wi 4  ⊤wtru 1542  ∃wex 1780  ∃*wmo 2535  ∃!weu 2565

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1796  ax-4 1810  ax-5 1911  ax-6 1968  ax-7 2009  ax-8 2115  ax-9 2123  ax-10 2146  ax-12 2182  ax-nul 5248  ax-pow 5307

This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-tru 1544  df-ex 1781  df-nf 1785  df-mo 2537  df-eu 2566

This theorem is referenced by: (None)