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 1.1.7 Tutorial: rings, polynomials, use command
When you want to do a computation in CoCoA-5, the first thing you need to do is tell CoCoA-5 in which ring to compute. The use command informs CoCoA-5 about this. The most convenient method does two things at once: it creates the polynomial ring, and then chooses that ring as the "current ring".

Once the correct current ring has been selected, you may type in polynomials using a natural syntax (with the caveat that you must use * to denote all products (e.g. between coefficients and indeterminates, or even between powers of indeterminates).

The most common coefficient fields are the rationals (denoted by QQ ) and small prime finite fields (denoted by ZZ/(p) ).

 Example
 ```/**/ use P ::= QQ[x,y]; // polys in x,y with coefficients in QQ /**/ (x+y)^2; x^2 + 2*x*y + y^2 /**/ use ZZ/(2)[a,b]; // polys in a,b with coefficients in ZZ/(2) /**/ (a+b)^2; a^2 + b^2 /**/ use QQ[x,y,z],lex; // polys in x,y,z, coeffs in QQ, term order "lex" /**/ x+y^2; x + y^2 ```