Use R ::= QQ[t,x,y,z];
I := Ideal(x,y);
M := 5;
N := 8;
T := M+N;
T;
13

T := T+1;  note that T occurs on the right, also
T;
14

L := [1,2,3];
L[2] := L[3];
L;
[1, 3, 3]

P := Record[F = xz];
P.Degree := Deg(P.F);
P;
Record[Degree = 2, F = xz]

Use S ::= QQ[a,b];
I;  I is labeled by R since it depends on R
R :: Ideal(x, y)

T;  T is not labeled by R
14

J := R:: Ideal(x^2y);  J contains an object dependent on R
J;  since the ring S is active, J is labeled by R
R :: Ideal(x^2  y)

Use R;
J;
Ideal(x^2  y)

