Theorem ublemc2 711

Description: Commutation theorem for biimplication.

Assertion

Ref	Expression
ublemc2	b C (a ≡ b)

Proof of Theorem ublemc2

Step	Hyp	Ref	Expression
1		ublemc1 710	. 2 b C (b ≡ a)
2		bicom 88	. 2 (b ≡ a) = (a ≡ b)
3	1, 2	cbtr 174	1 b C (a ≡ b)

Syntax hints:   C wc 3   ≡ tb 5

This theorem was proved from axioms:  ax-a1 29  ax-a2 30  ax-a3 31  ax-a4 32  ax-a5 33  ax-r1 34  ax-r2 35  ax-r4 36  ax-r5 37  ax-r3 421

This theorem depends on definitions:  df-b 38  df-a 39  df-t 40  df-f 41  df-le1 122  df-le2 123  df-c1 124  df-c2 125

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