Theorem u4lemc3 676

Description: Commutation theorem for non-tollens implication.

Hypothesis

Ref	Expression
ulemc3.1	a C b

Assertion

Ref	Expression
u4lemc3	a C (b ->4 a)

Proof of Theorem u4lemc3

Step	Hyp	Ref	Expression
1		u4lemc1 665	1 a C (b ->4 a)

Syntax hints:   C wc 3   ->4 wi4 16

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-i4 46  df-le1 122  df-le2 123  df-c1 124  df-c2 125

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