|
13739
|
1 |
(*<*)
|
|
|
2 |
theory Snoc = Main:
|
|
|
3 |
(*>*)
|
|
|
4 |
subsection {* Lists *}
|
|
|
5 |
|
|
|
6 |
text {*
|
|
|
7 |
Define a primitive recursive function @{text snoc} that appends an element
|
|
|
8 |
at the \emph{right} end of a list. Do not use @{text"@"} itself.
|
|
|
9 |
*}
|
|
|
10 |
|
|
|
11 |
consts
|
|
|
12 |
snoc :: "'a list => 'a => 'a list"
|
|
|
13 |
|
|
|
14 |
text {*
|
|
|
15 |
Prove the following theorem:
|
|
|
16 |
*}
|
|
|
17 |
|
|
|
18 |
theorem rev_cons: "rev (x # xs) = snoc (rev xs) x"
|
|
|
19 |
(*<*)oops(*>*)
|
|
|
20 |
|
|
|
21 |
text {*
|
|
|
22 |
Hint: you need to prove a suitable lemma first.
|
|
|
23 |
*}
|
|
|
24 |
|
|
|
25 |
(*<*)
|
|
|
26 |
end
|
|
|
27 |
(*>*)
|