Theorem aecom 1946

Description: Commutation law for identical variable specifiers. The antecedent and consequent are true when x and y are substituted with the same variable. Lemma L12 in [Megill] p. 445 (p. 12 of the preprint). (Contributed by NM, 5-Aug-1993.)

Assertion

Ref	Expression
aecom	⊢ (∀x x = y → ∀y y = x)

Proof of Theorem aecom

Step	Hyp	Ref	Expression
1		ax10 1944	1 ⊢ (∀x x = y → ∀y y = x)

Syntax hints:   → wi 4  ∀wal 1540

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1546  ax-5 1557  ax-17 1616  ax-9 1654  ax-8 1675  ax-6 1729  ax-7 1734  ax-11 1746  ax-12 1925

This theorem depends on definitions:  df-bi 177  df-an 360  df-tru 1319  df-ex 1542  df-nf 1545

This theorem is referenced by:  aecoms  1947  naecoms  1948  sbcom  2089