3 \def\isabellecontext{prime{\isacharunderscore}def}%
18 \begin{isamarkuptext}%
20 A common mistake when writing definitions is to introduce extra free
21 variables on the right-hand side. Consider the following, flawed definition
22 (where \isa{dvd} means ``divides''):
24 \ \ \ \ \ {\isachardoublequote}prime\ p\ {\isasymequiv}\ {\isadigit{1}}\ {\isacharless}\ p\ {\isasymand}\ {\isacharparenleft}m\ dvd\ p\ {\isasymlongrightarrow}\ m\ {\isacharequal}\ {\isadigit{1}}\ {\isasymor}\ m\ {\isacharequal}\ p{\isacharparenright}{\isachardoublequote}%
26 \par\noindent\hangindent=0pt
27 Isabelle rejects this ``definition'' because of the extra \isa{m} on the
28 right-hand side, which would introduce an inconsistency (why?).
29 The correct version is
31 \ \ \ \ \ {\isachardoublequote}prime\ p\ {\isasymequiv}\ {\isadigit{1}}\ {\isacharless}\ p\ {\isasymand}\ {\isacharparenleft}{\isasymforall}m{\isachardot}\ m\ dvd\ p\ {\isasymlongrightarrow}\ m\ {\isacharequal}\ {\isadigit{1}}\ {\isasymor}\ m\ {\isacharequal}\ p{\isacharparenright}{\isachardoublequote}%
52 %%% TeX-master: "root"