--- a/doc-src/TutorialI/basics.tex Wed Jul 31 16:10:24 2002 +0200
+++ b/doc-src/TutorialI/basics.tex Wed Jul 31 17:42:38 2002 +0200
@@ -281,7 +281,7 @@
variables are automatically renamed to avoid clashes with free variables. In
addition, Isabelle has a third kind of variable, called a \textbf{schematic
variable}\index{variables!schematic} or \textbf{unknown}\index{unknowns},
-which must a~\isa{?} as its first character.
+which must have a~\isa{?} as its first character.
Logically, an unknown is a free variable. But it may be
instantiated by another term during the proof process. For example, the
mathematical theorem $x = x$ is represented in Isabelle as \isa{?x = ?x},