Default GCD



> Assume that A is an integral domain (that is, I is prime) and let K
> be its field of fractions.

Just to show that this is a real concern and that zero-divisors might
be introduced even in cases where perhaps one wouldn't expect them:

(C1) algebraic:true;
(D1) 				     TRUE
(C2) tellrat(u^2=t-1,v^2=t+1);
			     2		 2
(D2) 			   [v  - t - 1, u  - t + 1]
(C3) x:rat(sqrt(2)*sqrt(u*v+t));
(D3)/R/ 		     SQRT(2) SQRT(u v + t)
(C4) e:rat(x-u-v);
(D4)/R/ 		 SQRT(2) SQRT(u v + t) - v - u
(C5) f:rat(x+u+v);
(D5)/R/ 		 SQRT(2) SQRT(u v + t) + v + u
(C6) is(e=0);
(D6) 				     FALSE
(C7) is(f=0);
(D7) 				     FALSE
(C8) is(e*f=0);
(D8) 				     TRUE

Wolfgang