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i use a not good example's polynomials to illustrate the idea

T := lexdeg([a,b,c],[e1,e2, e3]);
GB := Basis([e1-u1, e2-u2, e3-u3],T);
result := NormalForm(a*b+b*c, GB, T);

now result is to express a*b+b*c in terms of e1, e2, e3 which represent u1, u2, u3.

is it possible to use preimage to find possible u1,u2,u3 if unknown u1,u2,u3 and given known eqx?

How to use preimage to find possible eqx if given known u1,u2,u3 to find eqx in NormalForm(eqx, GB, T)?


what i confused in code below is that if i know it in terms of -1*e1+2*e2+*e3

it already can be used to find eqx, it seems reasonable to put source1list as unknown to find eqx  or find unknown eq1, eq2, eq3 if given known eqx.

source1 := PolynomialRing([e1, e2, e3]);
target1 := PolynomialRing([a, b, c]);
source1list := [-1*e1+2*e2+*e3, -1*e1+2*e2+*e3, -1*e1+2*e2+*e3];
target1list := [eq1, eq2, eq3];
cs := PolynomialMapPreimage(target1list, source1list, source1, target1);
Info(cs, source1);
[[e1-e2-e3], [1]]

follow Computing non-commutative Groebner bases and Groebner bases for modules

in maple 12

Error, (in Groebner:-Basis) the first argument must be a list or set of polynomials or a PolynomialIdeal


then i find in maple 15 help file is changed from module M := [seq(Vector(subsop(i+1 = 1, [F[i], 0, 0, 0])), i = 1 .. 3)]

to array M := [seq( s^3*F[i] + s^(3-i), i=1..3)];

though it can run, but when apply other example can not run

such as


F := [x+y+z, x*y+y*z+z*x, x*y*z-1];
M := [seq( s^3*F[i] + s^(3-i), i=1..3)];
M := [[x*y,y,x],[x^2+x,y+x^2,y],[-y,x,y],[x^2,x,y]];
A := poly_algebra(x,y,z,s);
T := MonomialOrder(A, lexdeg([s], [x,y,z]), {s});
G := Groebner[Basis](M, T);
Error, (in Groebner:-Basis) the first argument must be a list or set of polynomials or a PolynomialIdeal

G1 := select(proc(a) evalb(degree(a,s)=3) end proc, G);
[seq(Vector([seq(coeff(j,s,3-i), i=0..3)]), j=G1)];
C := Matrix([seq([seq(coeff(j,s,3-i), i=1..3)], j=G1)]);
GB := map(expand, convert(C.Vector(F), list));
Groebner[Basis](F, tdeg(x,y,z));

#page 320 and 322 of book Singular introduction to commutative algebra

it return too many recursion 


hilbertseries([a+a*c, a+a*b, a+b+c]);

eq1 := a+a*c;

eq2 := a+a*b;

eq3 := a+b+c;

eq1a := Homogenize(eq1, h);

eq2a := Homogenize(eq2, h);

eq3a := Homogenize(eq3, h);


GB := Basis([eq1a,eq2a,eq3a], T3); #a


#MonomialHilbertPoincare(LeadingMonomial(GB[1],T3), LeadingMonomial(GB[2],T3), LeadingMonomial(GB[3],T3));



MonomialHilbertPoincare := proc (I3)

#I3:=[LeadingMonomial(GB[1],T3), LeadingMonomial(GB[2],T3), LeadingMonomial(GB[3],T3)];


varj := [h,c,b,a];

I2 := InterReduce(I3, T2);

s := nops(I2);

if I2[1] = 0 then return 1 end if:

if I2[1] = 1 then return 0 end if:

if degree(I2[s]) = 1 then return (1-varj[1])^s end if:

lt := LeadingTerm(I2[s],T2);

leadexp := [degree(lt[2],h),degree(lt[2],c),degree(lt[2],b),degree(lt[2],a)];

j := 1;

for z from 1 to nops(leadexp) do

                if leadexp[j] = 0 then

                                j := j + 1;

                end if:


finallist := [];

for z from 1 to nops(GB) do

                finallist := [op(finallist), GB[z]+varj[j]];


quotientlist := Generators(Quotient(GB, varj[j]));

finallist2 := [];

for z from 1 to nops(quotientlist) do

                finallist2 := [op(finallist2), op(z,quotientlist)];


return MonomialHilbertPoincare(finallist) + varj[1]*MonomialHilbertPoincare(finallist2);

end proc;

F:=[LeadingMonomial(GB[1],T3), LeadingMonomial(GB[2],T3), LeadingMonomial(GB[3],T3)];



Let Poly2 denote the vector space of polynomials

(with real coefficients) of degree less than 3.

Poly2 = {a1t^2+ a2 t+ a3 |a1; a2; a3 €R}

You may assume that {1,t; t^2}is a basis for Poly2.

(1) Show that L1 = {t^2 + 1; t-2 ; t + 3}and L2 = {2 t^2 + t; t^2 + 3; t}

are bases for Poly2.

(2) Let = 8t^2- 4+ 6 and = 7t^2- t + 9. Find the coordinates for

and with respect to the basis L1 and with respect to the basis L2

(3) find the coordinate change matrix P from the basis L1 to the basis L2.find P^-1

Just I answer part (1) can you help me to answer 2 and 3 

 V = {(2a + b + c, 3a + b + 2c, 2a + c, b + 7c)|a, b, c ∈ R} forms a subspace of R^4 
 Show that {(2, 3, 2, 0),(1, 1, 0, 1),(0, 1, 1, 6)} is an (ordered) basis B for V . 

toally confused on how to do this??..please help!!

I am trying to take out the intersection between two bases from one of the original basis. I have two matrices (A and B) and want to find the intesection between the range (or column space) of A and the null space of B. The range of A is 


For some reason, the column space is not presented as a list, but with square brakes, so I convert this into a list of vectors:

X2:=SumBasis([X1[1],X1[2]])    %If I use the command Basis, it returns again square brakets, not sure why... 

The null space of B



X5:= X2\cap X4 % I am using latex code for the intersection symbol...

The result is the empty set! Evidently, X2 and X3 are differnt bases.

Any help would be really welcome! Many thanks!


So im trying to write a maple script that computes the Jordan form of a given (3x3)- matrix
A. If {a,b,c} is a basis with respect to which A is in Jordan form, then I'm trying to make it
plot the three lines spanned by a, b and c, in the standard coordinate system. I was hinted to use plot3d here.

sidenote: I know how to compute the jordan matrix of A, such by find the eigen vectors and generalised eigen vectors and putting them in as columns in a 3x3 matrix say S,   where S is invertible    then  (S^-1)*(A)*(S) = (J).

Thanks in advance. <3

In that attached file is a multip step problem that involves graphing a right circular cylinder using transtion matrices and orthonormal basis. I have completed the hole question minus the very last part which is asking for new parametric equations for the cylinder if its center point is located at (-2, 10, 3) instead of the origin.

Any ideas on how to do this will be greatly appreciated.

Find parametric equations for the right circular cylinder having radius 3, length 12, whose axis is the z-axis and whose bottom edge lies in the plane: z=0.



Do I just define B={u1, u2, u3} being a basis for R3 and use the gram-schmidt operator to find the parametric equations?

I know that would give me an orthonrmal basis, but how do i find parametirc equations?

I’m trying to figure out how to find a basis for a subspace, V, of Rdefined by V = {(x, y, z)l(2x-3y+6z=0)}


I’m using the student linear algebra module for maple 17


I’ve tried defining the subspace and asking for the basis of V but I always get an error code.


I’ve tried consulting the maple website and looking through their help menu, but can’t find anything that answers how to find a basis... At least a basis from the subspace defined in my problem.

I know how to find a basis for the subspace by hand but not with maple.

Any help will be greatly appreciated. 

computer a Gröbner basis for <f_[1] = x^2*y - 2*y*z + 1, f_[2] = x*y^2-z^2+ 2*x,  f_[3] = y^2*z - x^2+ 5 > belong to Q[x,y,z], using ≺= <_grlex with x≺y≺z. compare your output to the Gröbner basis the Maple computers with a different order.

Two questions:

The algortihms that Groebner[Basis] uses at each step computes some "tentative" or "pseudo-basis". The "tentative" basis is not a Groebner basis but it is in the ideal generated by the original system of polynomial eq.

1) Is this correct ? Provided this is correct, then

2) How can one retrive the last "tentative" basis?
 If I just use timelimit I can abort the computations but how can one retrive the last computation?


I have been struggling (reading Ore/Weyl Algebra documentation) to understand how to input a PDE system with polynomial coeff. in Weyl algebra notation so I can compute a Groebner basis for it. I would be very grateful if someone could  show, using the simple example below, which differential operators in Ore_algebra[diff_algebra] should one declare to express the system in Weyl algebra notation. The systems I'm working are more complicated but all have many dependent variables, f and g functions in this example:

pdesys:= [ x*diff( f(x,y,z),x)- z*diff( g(x,y,z),y) = 0, (x^2-y)*diff( f(x,y,z),z)- y*diff( g(x,y,z),z) = 0 ]

I am using the ColumnSpace command (from the LinearAlgebra package) to generate a basis for the column space of a matrix. Is there any way to "force" the command to express the basis in terms of columns of A and not in the canonical form with leading 1's?

For example, for


I would like to obtain the following basis for the column space:



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