Theorem equsb2 2035

Description: Substitution applied to an atomic wff. (Contributed by NM, 5-Aug-1993.)

Assertion

Ref	Expression
equsb2	|- [y / x]y = x

Proof of Theorem equsb2

Step	Hyp	Ref	Expression
1		sb2 2023	. 2 |- (A.x(x = y -> y = x) -> [y / x]y = x)
2		equcomi 1679	. 2 |- (x = y -> y = x)
3	1, 2	mpg 1548	1 |- [y / x]y = x

Syntax hints:   -> wi 4  [wsb 1648

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  df-sb 1649

This theorem is referenced by:  sbco  2083  sbidm  2085