diff -r 6eb185959aec -r ef2a8a3bae4a doc-src/TutorialI/Fun/fun0.thy --- a/doc-src/TutorialI/Fun/fun0.thy Thu Nov 08 13:23:04 2007 +0100 +++ b/doc-src/TutorialI/Fun/fun0.thy Thu Nov 08 13:23:19 2007 +0100 @@ -79,12 +79,8 @@ Isabelle's automatic termination prover for \isacommand{fun} has a fixed notion of the \emph{size} (of type @{typ nat}) of an argument. The size of a natural number is the number itself. The size -of a list is its length. In general, every datatype @{text t} comes -with its own size function (named @{text"t.size"}) which counts the -number of constructors in a term of type @{text t} --- more precisely -those constructors where one of the arguments is of the type itself: -@{const Suc} in the case of @{typ nat} and @{const "op #"} in the case -of lists. A recursive function is accepted if \isacommand{fun} can +of a list is its length. For the general case see \S\ref{sec:general-datatype}. +A recursive function is accepted if \isacommand{fun} can show that the size of one fixed argument becomes smaller with each recursive call.