fixed caption font;

--- a/doc-src/Logics/CTT.tex	Wed May 07 17:21:24 1997 +0200
+++ b/doc-src/Logics/CTT.tex	Wed May 07 18:35:56 1997 +0200
@@ -695,8 +695,8 @@
 \tdx{diff_succ_succ}    [| a:N;  b:N |] ==> succ(a) - succ(b) = a - b : N
 \tdx{diff_self_eq_0}    a:N ==> a - a = 0 : N
 \tdx{add_inverse_diff}  [| a:N;  b:N;  b-a=0 : N |] ==> b #+ (a-b) = a : N
+\end{ttbox}
 \caption{The theory of arithmetic} \label{ctt_arith}
-\end{ttbox}
 \end{figure}