| author | nipkow |
| Tue, 05 Sep 2000 13:53:39 +0200 | |
| changeset 9844 | 8016321c7de1 |
| parent 9792 | bbefb6ce5cb2 |
| child 11456 | 7eb63f63e6c6 |
| permissions | -rw-r--r-- |
| nipkow@8745 | 1 |
(*<*) |
| nipkow@8745 | 2 |
theory prime_def = Main:; |
| nipkow@8745 | 3 |
consts prime :: "nat \\<Rightarrow> bool" |
| nipkow@8745 | 4 |
(*>*) |
| nipkow@9844 | 5 |
text{*
|
| nipkow@9844 | 6 |
\begin{warn}
|
| nipkow@9844 | 7 |
A common mistake when writing definitions is to introduce extra free |
| nipkow@9844 | 8 |
variables on the right-hand side as in the following fictitious definition: |
| nipkow@9844 | 9 |
@{term[display,quotes]"prime(p) == 1 < p & (m dvd p --> (m=1 | m=p))"}
|
| nipkow@9792 | 10 |
where @{text"dvd"} means ``divides''.
|
| nipkow@9792 | 11 |
Isabelle rejects this ``definition'' because of the extra @{term"m"} on the
|
| nipkow@9458 | 12 |
right-hand side, which would introduce an inconsistency (why?). What you |
| nipkow@8745 | 13 |
should have written is |
| nipkow@9844 | 14 |
@{term[display,quotes]"prime(p) == 1 < p & (!m. m dvd p --> (m=1 | m=p))"}
|
| nipkow@9844 | 15 |
\end{warn}
|
| nipkow@8745 | 16 |
*} |
| nipkow@8745 | 17 |
(*<*) |
| nipkow@8745 | 18 |
end |
| nipkow@8745 | 19 |
(*>*) |