Re: [isabelle] question about "fun"
fun gener :: "'a list => (nat list * 'a list)"
gener_Cons: "gener (a # b # l) =
(if a = b then (0 # fst (gener (b # l)), snd (gener (b # l)))
else (fst (gener l), snd (gener l)))"
|gener_Nil: "gener a = (, a)"
Somehow, the induction rule associated to the previous definition:
has the following aspect:
\<And> a b l. [| a = b ==> ?P (b # l); a = b ==> ?P (b # l); a
\<noteq> b ==> ?P l; a \<noteq> b ==> ?P l |] ==> ?P (a # b # l);
?P ; \<And>v. ?P [v] |]
==> ?P ?a0.0
I think you mean that you would prefer to have the case distinction a
= b vs a ~= b built into the induction rule, instead of having to do
it yourself each time you apply it. The function package never does
such things automatically, in order to have a predictable berhaviour.
If you know what rule you would like to see, you can also state it
yourself and use the "induct_scheme" method to derive it, usually
almost automatically. See ch. 5 of my thesis for details
This archive was generated by a fusion of
Pipermail (Mailman edition) and