diff -r 80a4d0742e98 -r aa75d24ba7d0 lemon/full_graph.h
--- a/lemon/full_graph.h	Sat Nov 01 19:22:18 2008 +0100
+++ b/lemon/full_graph.h	Mon Nov 03 22:30:21 2008 +0100
@@ -75,7 +75,7 @@
     typedef True FindArcTag;
 
     Arc findArc(Node s, Node t, Arc prev = INVALID) const {
-      return prev != INVALID ? arc(s, t) : INVALID;
+      return prev == INVALID ? arc(s, t) : INVALID;
     }
 
     class Node {