Gröbner Bases
Syzygies
Resolutions
Quantum Alg.
Left Maximality
Max. Twosided
Algebraic Dependency in Quantum Algebras - PLURAL code
We denote Q=q1/2 and set Q6=1 :
ring r=(0,Q),(a,b,c,d,x,y,z),dp;
minpoly=Q^4+Q^2+1;

//setting up the relations in r: matrix A[7][7]; matrix B[7][7]; int u,j; for(u=1;u<=7;u++) { for(j=u;j<=7;j++) {A[u,j]=1;} } A[5,6]=Q2; A[5,7]=1/Q2; A[6,7]=Q2; B[5,6]=-Q*z; B[5,7]=1/Q*y; B[6,7]=-Q*x; system("PLURAL",A,B); //the central elements: poly Cq=Q^4*x2+y2+Q^4*z2+Q*(1-Q^4)*x*y*z; poly C1=1/3*(x^3+x); poly C2=1/3*(y^3+y); poly C3=1/3*(z^3+z); ideal I=a-Cq,b-C1,c-C2,d-C3; I=std(I); I;
==> I[1]=z3-3*d+z
...
I[5]=a3+(81Q3+162Q)*bcd+(-Q2)*a2-9*b2-9*c2-9*d2
...
I[26]=bcdxy+(1/81Q3-1/81Q)*abx2y+(1/729Q3-4/729Q)*ax3y+(1/81Q3-1/81Q)*acxy2+
(1/81Q3+2/81Q)*aby3+(-2/729Q3-1/729Q)*axy3+(2/243Q2+4/243)*a2x2z+(-5/81Q3-4/81Q)*adxyz+
(-1/81Q2+1/81)*a2y2z+(1/9Q3+2/9Q)*abcz2+(7/81Q3+8/81Q)*acxz2+(-5/81Q3-7/81Q)*abyz2+
(22/729Q3+20/729Q)*axyz2+(2/243Q2+1/81)*a2z3+(-2/81Q3-1/81Q)*a2cx+(7/81Q2+4/81)*adx2+
(-2/81Q3-1/81Q)*a2by+(-13/729Q3-11/729Q)*a2xy+(1/27Q3+2/27Q)*b2xy+(1/27Q3+2/27Q)*c2xy+
(1/27Q3+2/27Q)*d2xy+(1/81Q2-5/81)*ady2+(-1/243Q2-1/243)*a3z+(4/81Q2+4/81)*abxz+
(-14/729Q2+8/729)*ax2z+(4/81Q2-2/81)*acyz+(-2/243Q2)*ay2z+(1/27Q2)*adz2-2/243*az3+
(1/27Q3+2/27Q)*abc+(5/81Q3+1/81Q)*acx+(-1/81Q3-1/27Q)*aby+(-1/729Q3-5/729Q)*axy+(1/243Q2+5/243)*a2z
From the output we read the wanted polynomial I[5] (only depending on a,b,c,d).

KL, 06/03 http://www.singular.uni-kl.de