--- a/doc-src/TutorialI/Rules/rules.tex Wed Jul 31 16:10:24 2002 +0200
+++ b/doc-src/TutorialI/Rules/rules.tex Wed Jul 31 17:42:38 2002 +0200
@@ -4,7 +4,7 @@
This chapter outlines the concepts and techniques that underlie reasoning
in Isabelle. Until now, we have proved everything using only induction and
-simplification, but any serious verification project require more elaborate
+simplification, but any serious verification project requires more elaborate
forms of inference. The chapter also introduces the fundamentals of
predicate logic. The first examples in this chapter will consist of
detailed, low-level proof steps. Later, we shall see how to automate such