The operators +, -, *, / are used for addition, subtraction,
multiplication and division of two cyclotomics; note that division by
0 causes an error.
+ and - can also be used as unary operators;
^ is used for exponentiation of a cyclotomic with an integer;
this is in general not equal to Galois conjugation.
gap> E(5) + E(3); (E(5) + E(5)^4) ^ 2; E(5) / E(3); E(5) * E(3);
-E(15)^2-2*E(15)^8-E(15)^11-E(15)^13-E(15)^14
-2*E(5)-E(5)^2-E(5)^3-2*E(5)^4
E(15)^13
E(15)^8
GAP 3.4.4