Re: [isabelle] ML "set simp_trace": Congruence Rule question
thank you for the explanation, but where does it come from? I checked
the HOL.thy theory and I did not see any such rule. Does it have a name?
Tobias Nipkow wrote:
The premise A = A == ?c is the instantiated premise of the congruence
?b == ?c
==> if ?b then ?x else ?y == if ?c then ?x else ?y
This rule is used to limit simplification of if-then-else to the
if-part, in this case A=A. Once that has become True, the if-then-else
collapses and its then-part can be simplified.
George Karabotsos wrote:
I am examining the simplifier's trace for the following lemma:
lemma "(if A=A then AV else if AA=BB then BV else CV) = AV"
There is a part of the trace I do not understand - specifically I am
talking about the following part:
Applying congruence rule:
A = A == ?c
==> if A = A then AV else if AA = BB then BV else CV ==
if ?c then AV else if AA = BB then BV else CV
Where did the A =A == ?c rule came from?
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