Opened 14 years ago

Closed 14 years ago

#257 closed bug (duplicate)

example lift over Q(t): bad perfomance / hung machine

Reported by: seelisch Owned by: somebody
Priority: minor Milestone: 3-1-2 and higher
Component: singular-kernel Version: 3-1-1
Keywords: lift rational function field Cc:

Description

This was a forum entry from September 22, 2008; no problem for Magma but bad perf. in SINGULAR resp. hung machine:

ring R = (0,t), (w,x,y,z), dp; poly f = w3 + x3 + y3 + z3 + t*((w+x)*(w+2*y)*(w+3*z) + 3*x*y*(w+x+z)); ideal jac = jacob(f); print(lift(jac, x4));

Change History (2)

comment:1 Changed 14 years ago by seelisch

Magma V2.16-11 gives normal form (plus coefficients for GB elements to arrive at this normal form) immediately:

Q<s> := PolynomialRing?(Rationals()); F<t> := FieldOfFractions?(Q);

R := PolynomialRing?(F, 4, "grevlex"); AssignNames?(~R, ["w", "x", "y", "z"]); w := R.1; x := R.2; y := R.3; z := R.4;

f := w3 + x3 + y3 + z3 + t*((w+x)*(w+2*y)*(w+3*z) + 3*x*y*(w+x+z)); jac := JacobianIdeal?(f); j := GroebnerBasis?(jac);

n, C := NormalForm?(x4, j);

n; C;

comment:2 Changed 14 years ago by hannes

Resolution: duplicate
Status: newclosed

see # 154

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