Theorem ska5 225

Description: Soundness theorem for Kalmbach's quantum propositional logic axiom KA5.

Assertion

Ref	Expression
ska5	((a ∩ b) ≡ (b ∩ a)) = 1

Proof of Theorem ska5

Step	Hyp	Ref	Expression
1		ancom 68	. 2 (a ∩ b) = (b ∩ a)
2	1	bi1 110	1 ((a ∩ b) ≡ (b ∩ a)) = 1

Syntax hints:   = wb 1   ≡ tb 5   ∩ wa 7  1wt 9

This theorem was proved from axioms:  ax-a1 29  ax-a2 30  ax-a5 33  ax-r1 34  ax-r2 35  ax-r4 36  ax-r5 37

This theorem depends on definitions:  df-b 38  df-a 39  df-t 40  df-f 41

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