Subject: Help

From: Hongmei Chi <[email-masked]>
Date: Tue, 15 Jun 1999 15:35:12 -0400

I try to write a simple program to define a plus by myself. 

sum(X,0,X).
sum(W, f(Y), f(Z)):-sum(W,Y,Z).

This doesnot work and just keep telling me to refine sum.
Please tell me the reason.

The goal of this program is to define sum(X,Y,Z) : Z=X+Y,
Not by using the build_in predictors, such as plus or is.

Thank you