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CanonicalHom

canonical homomorphism

Syntax 
CanonicalHom(R: RING, S: RING): RINGHOM

Description
CanonicalHom(R, S) -- where R and S are rings, gives the canonical homomorphism from R to S. Currently it works only on the most natural constructions: 
ZZ -> S    QQ -> S
R -> R/I   R -> FractionFiels(R)
R -> R[x[1..N]]


Example 
/**/ Use R ::= QQ[x,y];
/**/ RmodI := NewQuotientRing(R, ideal(x^2-1));

/**/ phi := CanonicalHom(R, RmodI);
/**/ phi(x^3*y);
(x*y)
/**/ RingOf(It) = RmodI;
true

/**/ RingElem(RmodI, x^3*y);  -- same as phi(x^3*y)
			      -- internally computes CanonicalHom

See Also