/* 
	A declarative language for specifying geometric problems
		and geometric theorem proving
 */

/* Conventions:
   *    Points and angles are denoted with a symbol;
   *	If A is a point then xA, yA denote its x and y coordinates;
   *    If A is an angle then cA and sA denote ist cos and sin
   *    If A and B are points than lA_B denotes the distance from A to B

A specification of a geometric problem will look like this
begin_hypotheses();
parallel(A,B,C,D);
parallel(A,C,B,D);
angle(P,A,B,C);
end_hypotheses();

....
*/