CoCoA » CoCoA-5

I wanted to do in CoCoA-5 an example/exercise from Martin Kreuzer's lecture course on computer algebra.
It turned out to be more awkward than I expected.

Can we make it easier?

The example was simply to compute the kernel of the algebra hom from @QQ[z]@ which maps @z@ to @(1+sqrt(5))/2@.

The problem I had was finding a neat way to create the hom (incl. having to look things up in the manual).

*2020-02* solution:
<pre>
/**/ phi := PolyAlgebraHom(NewPolyRing(QQ,"x"),
NewQuotientRing(NewPolyRing(QQ,"y"), "y^2-5"),
"(1+y)/2");
/**/ ker(phi);
</pre>