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Computing a formula in SAGE

asked 2019-08-20 01:22:31 +0200

Vochau gravatar image

Fix the positive integer numbers $t_1, t_2, t_3,t_4, t_5.$ We have the following formula:

$$ S= \sum_{i, j, h, m, k_1 + k_2+k_3+k_4 = i-t_1, \ell_1+\ell_2 + \ell_3 = j -t_2 + k_4, u_1 + u_2 = h - t_3+k_3+\ell_3 }M_1.M_2.M_3. M_4,$$ where

$$ M_1 = \binom{t_5-k_1}{k_1}\binom{t_4-k_2}{k_2}\binom{t_3-k_3}{k_3}\binom{t_2-k_4}{k_4}$$ $$ M_2 = \binom{t_5-k_1-\ell_1}{\ell_1}\binom{t_4-k_2-\ell_2}{\ell_2}\binom{t_3-k_3-\ell_3}{\ell_3}$$ $$ M_3 = \binom{t_5-k_1-\ell_1-u_1}{u_1}\binom{t_4-k_2-\ell_2-u_2}{u_2};$$ $$ M_4=\binom{t_1+t_2+t_3+t_4 +t_5-i - j-h-m}{m - t_4 + k_2+ \ell_2 + u_2}.\lambda_i\lambda_j\lambda_h\lambda_m\lambda_{t_1+t_2 + t_3+t_4+t_5 - i - j-h-m}$$ Here, the binomial factors $\binom{n}{k}$ mod 2 and the value of $S$ mod 2. By convention, $\binom{n}{k} \equiv 0$ (mod 2) if either $k < 0$ or $n < 0$ or $k > n.$

I don't how to construct this formula in SAGE. Can someone show me how to compute it using SAGE?

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Comments

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What are $\lambda$ and what are the bounds for the other variables? If it is an infinite series then you will want to compute a single coefficient first. Also a source would help.

rburing gravatar imagerburing ( 2019-08-20 07:37:29 +0200 )edit

Thank you very much! The number $\lambda$ is fixed.

Vochau gravatar imageVochau ( 2019-08-20 10:25:21 +0200 )edit
1

If $\lambda$ is a number then what do the subscripts mean? Are $i,j,h,m,k_1,k_2,k_3,k_4,\ell_1,\ell_2,\ell_3,u_1,u_2$ nonnegative? Alternatively/additionally, where exactly does this formula come from? (Probably the source will answer my questions.)

rburing gravatar imagerburing ( 2019-08-20 11:51:08 +0200 )edit

Yes, the subscripts $i, j, h, m, k_1, k_2, k_3, k_4, \ell_1, \ell_2, \ell_3, u_1, u_2$ are nonnegative. Here $\lambda$ is fixed. I hope that you can help me set up the above formula in Sage. Thank you very much!

Vochau gravatar imageVochau ( 2019-08-20 12:58:02 +0200 )edit
1

Is $S$ a polynomial of degree 5 in the infinitely many variables $\lambda_n$? Are $k_1\leqslant k_2 \leqslant k_3 \leqslant k_4$ and $\ell_1 \leqslant \ell_2 \leqslant \ell_3$ and $u_1 \leqslant u_2$ or not? (That is, ordered partitions or all partitions?)

rburing gravatar imagerburing ( 2019-08-20 13:37:21 +0200 )edit
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answered 2019-08-20 16:27:09 +0200

rburing gravatar image

updated 2019-08-21 11:04:41 +0200

This is a polynomial of degree $5$ in the noncommutative variables $\lambda_n$ where the sum of the indices in each monomial is $t_1+t_2+t_3+t_4+t_5$.

It seems Sage doesn't easily generate partitions of $n$ into $k$ nonnegative integers, so we implement this helper function for it (we partition $n+k$ into $k$ positive integers and subtract 1 from each one):

def nonnegative_partitions(n, length):
    from itertools import permutations
    for part in Partitions(n+length, length=length):
        seen = set([])
        for shuffled_part in permutations(part):
            shuffled_part = tuple(x-1 for x in shuffled_part)
            if not shuffled_part in seen:
                yield shuffled_part
                seen.add(shuffled_part)

Here we also take care that $4 = 2+2$ is counted only once. You can implement the formula as:

def S(t):
    F2 = GF(2)
    Lamb = FreeAlgebra(F2, sum(t)+1, names='l_')
    lamb = Lamb.gens()
    result = Lamb.zero()
    for indices in nonnegative_partitions(sum(t), length=5):
        (i,j,h,m,idc) = indices
        for k in nonnegative_partitions(i-t[0], length=4):
            M1 = F2(binomial(t[4]-k[0], k[0]) * binomial(t[3]-k[1], k[1]) * binomial(t[2]-k[2], k[2]) * binomial(t[1]-k[3], k[3]))
            for l in nonnegative_partitions(j-t[1]+k[3], length=3):
                M2 = F2(binomial(t[4]-k[0]-l[0], l[0]) * binomial(t[3]-k[1]-l[1],l[1]) * binomial(t[2]-k[2]-l[2],l[2]))
                for u in nonnegative_partitions(h-t[2]+k[2]+l[2], length=2):
                    M3 = F2(binomial(t[4]-k[0]-l[0]-u[0], u[0]) * binomial(t[3]-k[1]-l[1]-u[1],u[1]))
                    M4 = F2(binomial(sum(t)-sum([i,j,h,m]), m-t[3]+k[1]+l[1]+u[1]))
                    result += M1*M2*M3*M4*lamb[i]*lamb[j]*lamb[h]*lamb[m]*lamb[idc]
    return result

For example,

sage: S((1,2,3,4,5))
l_1*l_2*l_3*l_4*l_5 + l_1*l_2*l_3*l_6*l_3 + l_1*l_2*l_4*l_3*l_5 + l_1*l_2*l_4*l_5*l_3 + l_1*l_2*l_5*l_2*l_5 + l_1*l_2*l_6*l_3^2 + l_1*l_2*l_7*l_2*l_3 + l_1*l_2*l_8*l_1*l_3 + l_1*l_2*l_9*l_0*l_3 + l_1*l_3^3*l_5 + l_1*l_3^2*l_5*l_3 + l_1*l_3*l_5*l_3^2 + l_1*l_3*l_7*l_1*l_3 + l_1*l_4*l_3*l_2*l_5 + l_1*l_4^2*l_1*l_5 + l_1*l_4*l_7*l_0*l_3 + l_1*l_5*l_3^3 + l_1*l_6*l_0*l_3*l_5 + l_1*l_6*l_0*l_5*l_3 + l_1*l_6*l_1*l_2*l_5 + l_1*l_6*l_2*l_3^2 + l_1*l_6*l_5*l_0*l_3 + l_1*l_7*l_1*l_3^2 + l_1*l_8*l_0*l_1*l_5 + l_1*l_10*l_1*l_0*l_3 + l_2*l_1*l_3*l_4*l_5 + l_2*l_1*l_3*l_6*l_3 + l_2*l_1*l_4*l_3*l_5 + l_2*l_1*l_4*l_5*l_3 + l_2*l_1*l_5*l_2*l_5 + l_2*l_1*l_6*l_3^2 + l_2*l_1*l_7*l_2*l_3 + l_2*l_1*l_8*l_1*l_3 + l_2*l_1*l_9*l_0*l_3 + l_2*l_3^2*l_2*l_5 + l_2*l_3*l_4*l_1*l_5 + l_2*l_3*l_7*l_0*l_3 + l_2*l_5*l_0*l_3*l_5 + l_2*l_5*l_0*l_5*l_3 + l_2*l_5*l_1*l_2*l_5 + l_2*l_5*l_2*l_3^2 + l_2*l_5^2*l_0*l_3 + l_2*l_7*l_0*l_1*l_5 + l_2*l_9*l_1*l_0*l_3 + l_3*l_1*l_3^2*l_5 + l_3*l_1*l_3*l_5*l_3 + l_3*l_1*l_5*l_3^2 + l_3*l_1*l_7*l_1*l_3 + l_3*l_2*l_3*l_2*l_5 + l_3*l_2*l_4*l_1*l_5 + l_3*l_2*l_7*l_0*l_3 + l_3^3*l_1*l_5 + l_3^5 + l_3*l_5*l_1*l_3^2 + l_3*l_6*l_0*l_1*l_5 + l_4*l_0*l_3^2*l_5 + l_4*l_0*l_3*l_5*l_3 + l_4*l_0*l_5*l_3^2 + l_4*l_0*l_7*l_1*l_3 + l_4*l_2*l_3*l_1*l_5 + l_4*l_3*l_0*l_3*l_5 + l_4*l_3*l_0*l_5*l_3 + l_4*l_3*l_1*l_2*l_5 + l_4*l_3*l_2*l_3^2 + l_4*l_3*l_5*l_0*l_3 + l_4^2*l_1*l_3^2 + l_4*l_7*l_1*l_0*l_3 + l_5*l_0*l_3*l_2*l_5 + l_5*l_0*l_4*l_1*l_5 + l_5*l_0*l_7*l_0*l_3 + l_5*l_1*l_3^3 + l_5*l_3*l_1*l_3^2 + l_5*l_4*l_3*l_0*l_3 + l_5*l_6*l_1*l_0*l_3 + l_6*l_0*l_3*l_1*l_5 + l_6*l_3*l_0*l_1*l_5 + l_6*l_3^2*l_0*l_3 + l_6*l_5*l_1*l_0*l_3 + l_8*l_0*l_1*l_3^2 + l_8*l_1*l_0*l_1*l_5 + l_8*l_1*l_3*l_0*l_3 + l_9*l_0*l_3*l_0*l_3

When you compute S(t) for several t with different sum(t) then they will belong to different FreeAlgebras (with different number of generators $\lambda_n$), but the names of the generators are "compatible", so adding elements should coerce them into the larger parent FreeAlgebra. Unfortunately this doesn't work (yet), so you have to use a workaround like this:

sage: S_1 = S((1,1,1,3,4)); S_2 = S((1,2,3,4,5)); S_3 = S((1,1,1,6,6))
sage: S_2.parent()
Free Algebra on 16 generators (l_0, l_1, l_2, l_3, l_4, l_5, l_6, l_7, l_8, l_9, l_10, l_11, l_12, l_13, l_14, l_15) over Finite Field of size 2
sage: S_2.parent() == S_3.parent() # the biggest FreeAlgebra that contains all of them
True
sage: S_2.parent()(str(S_1)) + S_2 + S_3
l_1^3*l_3*l_4 + l_1^3*l_4*l_3 + l_1^3*l_5*l_2 + l_1^3*l_6^2 + l_1^3*l_7*l_5 + l_1^3*l_9*l_3 + l_1^2*l_2*l_3^2 + l_1^2*l_2*l_5*l_6 + l_1^2*l_3^2*l_2 + l_1^2*l_3*l_4*l_1 + l_1^2*l_3*l_5^2 + l_1^2*l_3*l_7*l_3 + l_1^2*l_4*l_3*l_6 + l_1^2*l_4^2*l_5 + l_1^2*l_5*l_0*l_3 + l_1^2*l_5*l_1*l_2 + l_1^2*l_5*l_3*l_5 + l_1^2*l_7*l_0*l_1 + l_1^2*l_7*l_3^2 + l_1^2*l_8*l_0*l_5 + l_1^2*l_8*l_2*l_3 + l_1*l_2*l_1*l_3^2 + l_1*l_2*l_1*l_5*l_6 + l_1*l_2*l_3^2*l_6 + l_1*l_2*l_3*l_6*l_3 + l_1*l_2*l_4*l_3*l_5 + l_1*l_2*l_4*l_5*l_3 + l_1*l_2*l_5*l_2*l_5 + l_1*l_2*l_6*l_3^2 + l_1*l_2*l_7*l_0*l_5 + l_1*l_2*l_8*l_1*l_3 + l_1*l_2*l_9*l_0*l_3 + l_1*l_3*l_0*l_3^2 + l_1*l_3*l_0*l_5*l_6 + l_1*l_3*l_2*l_3*l_1 + l_1*l_3*l_2*l_3*l_6 + l_1*l_3*l_2*l_4*l_5 + l_1*l_3^2*l_0*l_3 + l_1*l_3^2*l_1*l_2 + l_1*l_3^3*l_5 + l_1*l_3^2*l_5*l_3 + l_1*l_3*l_5*l_3^2 + l_1*l_3*l_6*l_0*l_5 + l_1*l_3*l_6*l_2*l_3 + l_1*l_4*l_2*l_3*l_5 + l_1*l_4*l_3*l_2*l_5 + l_1*l_4^2*l_1*l_5 + l_1*l_4*l_6*l_1*l_3 + l_1*l_4*l_7*l_0*l_3 + l_1*l_5*l_0*l_3*l_1 + l_1*l_5*l_0*l_3*l_6 + l_1*l_5*l_0*l_4*l_5 + l_1*l_5*l_1*l_3*l_5 + l_1*l_5*l_3*l_0*l_1 + l_1*l_5*l_3^3 + l_1*l_5*l_4*l_0*l_5 + l_1*l_5*l_4*l_2*l_3 + l_1*l_6*l_0*l_5*l_3 + l_1*l_6*l_1*l_2*l_5 + l_1*l_6*l_2*l_3^2 + l_1*l_6*l_4*l_1*l_3 + l_1*l_6*l_5*l_0*l_3 + l_1*l_7*l_1*l_0*l_1 + l_1*l_7*l_1*l_3^2 + l_1*l_8*l_0*l_1*l_5 + l_1*l_9*l_0^2*l_5 + l_1*l_9*l_0*l_2*l_3 + l_1*l_9*l_1^2*l_3 + l_1*l_10*l_0*l_1*l_3 + l_1*l_10*l_1*l_0*l_3 + l_2*l_1^2*l_3^2 + l_2*l_1^2*l_5*l_6 + l_2*l_1*l_3^2*l_6 + l_2*l_1*l_3*l_6*l_3 + l_2*l_1*l_4*l_3*l_5 + l_2*l_1*l_4*l_5*l_3 + l_2*l_1*l_5*l_2*l_5 + l_2*l_1*l_6*l_3^2 + l_2*l_1*l_7*l_0*l_5 + l_2*l_1*l_8*l_1*l_3 + l_2*l_1*l_9*l_0*l_3 + l_2*l_3*l_2*l_3*l_5 + l_2*l_3^2*l_2*l_5 + l_2*l_3*l_4*l_1*l_5 + l_2*l_3*l_6*l_1*l_3 + l_2*l_3*l_7*l_0*l_3 + l_2*l_5*l_0*l_5*l_3 + l_2*l_5*l_1*l_2*l_5 + l_2*l_5*l_2*l_3^2 + l_2*l_5*l_4*l_1*l_3 + l_2*l_5^2*l_0*l_3 + l_2*l_7*l_0*l_1*l_5 + l_2*l_9*l_0*l_1*l_3 + l_2*l_9*l_1*l_0*l_3 + l_3*l_0*l_1*l_3^2 + l_3*l_0*l_1*l_5*l_6 + l_3*l_0*l_3^2*l_6 + l_3*l_0*l_3*l_4*l_5 + l_3*l_0*l_7*l_0*l_5 + l_3*l_0*l_7*l_2*l_3 + l_3*l_1*l_3^2*l_5 + l_3*l_1*l_3*l_5*l_3 + l_3*l_1*l_5*l_3^2 + l_3*l_1*l_7*l_1*l_3 + l_3*l_2*l_1*l_3*l_1 + l_3*l_2*l_1*l_3*l_6 + l_3*l_2*l_1*l_4*l_5 + l_3*l_2^2*l_3*l_5 + l_3*l_2*l_3*l_2*l_5 + l_3*l_2*l_4*l_1*l_5 + l_3*l_2*l_5*l_0*l_5 + l_3*l_2*l_5*l_2*l_3 + l_3*l_2*l_6*l_1*l_3 + l_3*l_2*l_7*l_0*l_3 + l_3^2*l_0*l_3*l_1 + l_3^2*l_0*l_3*l_6 + l_3^2*l_0*l_4*l_5 + l_3^3*l_0*l_1 + l_3^3*l_1*l_5 + l_3^5 + l_3^2*l_4*l_0*l_5 + l_3^2*l_4*l_2*l_3 + l_3^2*l_5*l_1*l_3 + l_3*l_4*l_3*l_0*l_5 + l_3*l_4*l_3*l_2*l_3 + l_3*l_5*l_1*l_3^2 + l_3*l_5*l_3*l_1*l_3 + l_3*l_6*l_0*l_1*l_5 + l_3*l_7*l_0^2*l_5 + l_3*l_7*l_0*l_2*l_3 + l_3*l_7*l_1^2*l_3 + l_4*l_0*l_3^2*l_5 + l_4*l_0*l_3*l_5*l_3 + l_4*l_0*l_5*l_3^2 + l_4*l_0*l_7*l_1*l_3 + l_4*l_2*l_1*l_3*l_5 + l_4*l_2*l_3*l_1*l_5 + l_4*l_2*l_5*l_1*l_3 + l_4*l_3*l_0*l_5*l_3 + l_4*l_3*l_1*l_2*l_5 + l_4*l_3*l_2*l_3^2 + l_4*l_3*l_4*l_1*l_3 + l_4*l_3*l_5*l_0*l_3 + l_4^2*l_1*l_3^2 + l_4^2*l_3*l_1*l_3 + l_4*l_7*l_0*l_1*l_3 + l_4*l_7*l_1*l_0*l_3 + l_5*l_0*l_1*l_3*l_1 + l_5*l_0*l_1*l_3*l_6 + l_5*l_0*l_1*l_4*l_5 + l_5*l_0*l_2*l_3*l_5 + l_5*l_0*l_3*l_2*l_5 + l_5*l_0*l_4*l_1*l_5 + l_5*l_0*l_5*l_0*l_5 + l_5*l_0*l_5*l_2*l_3 + l_5*l_0*l_6*l_1*l_3 + l_5*l_0*l_7*l_0*l_3 + l_5*l_1^2*l_3*l_5 + l_5*l_1*l_3^3 + l_5*l_1*l_5*l_1*l_3 + l_5*l_3*l_1*l_3^2 + l_5*l_3*l_2*l_0*l_5 + l_5*l_3*l_2^2*l_3 + l_5*l_4*l_2*l_1*l_3 + l_5*l_4*l_3*l_0*l_3 + l_5^2*l_0^2*l_5 + l_5^2*l_0*l_2*l_3 + l_5^2*l_1^2*l_3 + l_5*l_6*l_0*l_1*l_3 + l_5*l_6*l_1*l_0*l_3 + l_6*l_0*l_1*l_3*l_5 + l_6*l_0*l_3*l_1*l_5 + l_6*l_0*l_5*l_1*l_3 + l_6*l_3*l_0*l_1*l_5 + l_6*l_3*l_2*l_1*l_3 + l_6*l_3^2*l_0*l_3 + l_6*l_5*l_0*l_1*l_3 + l_6*l_5*l_1*l_0*l_3 + l_7*l_0^2*l_3*l_5 + l_7*l_0*l_4*l_1*l_3 + l_7*l_1*l_2*l_0*l_5 + l_7*l_1*l_2^2*l_3 + l_7*l_2^2*l_1*l_3 + l_8*l_0*l_1*l_3^2 + l_8*l_1*l_0*l_1*l_5 + l_8*l_1*l_2*l_1*l_3 + l_8*l_1*l_3*l_0*l_3 + l_9*l_0*l_2*l_1*l_3 + l_9*l_0*l_3*l_0*l_3 + l_11*l_0^2*l_1*l_3
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Comments

I have copied your code into Sage online https://sagecell.sagemath.org/. However, it reports an error File "<ipython-input-1-70610415ffb6>", line 26 sage: S((Integer(1),Integer(2),Integer(3),Integer(4),Integer(5))) ^ SyntaxError: invalid syntax</ipython-input-1-70610415ffb6>

Vochau gravatar imageVochau ( 2019-08-20 16:55:50 +0200 )edit

Try this example SageCell

rburing gravatar imagerburing ( 2019-08-20 17:08:12 +0200 )edit

Thank you very much!

Vochau gravatar imageVochau ( 2019-08-20 17:31:47 +0200 )edit

In the online version of Sagemath https://sagecell.sagemath.org/, for S((1,2,3,4,5)), it is not found the result.

Vochau gravatar imageVochau ( 2019-08-21 01:43:41 +0200 )edit

Moreover, the monomial $\lambda_a\lambda_b\lambda_c\lambda_d\lambda_e$ is not ordere partitions. More presely, the subscripts $a, b, c, d, e$ are not necessary to order partition. For example, $S = \lambda_1\lambda_3\lambda_2^2\lambda_4\lambda_5 + \lambda_3\lambda_2^2\lambda_1\lambda_4\lambda_5 + \lambda_1\lambda_2^2\lambda_3\lambda_4\lambda_5.$

Vochau gravatar imageVochau ( 2019-08-21 03:06:45 +0200 )edit

Yes, S((1,2,3,4,5)) takes a while, so you need to use a computer or other service like CoCalc. Do you mean the variables $\lambda_n$ do not commute? That is, $\lambda_1\lambda_2 \neq \lambda_2\lambda_1$? Then you should replace PolynomialRing by FreeAlgebra.

rburing gravatar imagerburing ( 2019-08-21 07:51:57 +0200 )edit

Yes, $\lambda_1\lambda_2\neq \lambda_2\lambda_1.$

Vochau gravatar imageVochau ( 2019-08-21 07:58:09 +0200 )edit

Thank you very much! Now, for example set S_1:=S((1,1,1,3,4)); S_2:=S((1,2,3,4,5)); S_3:=S((1,1,1,6,6)). How to compute S_1+S_2+S_3 (mod 2) in Sage?

Vochau gravatar imageVochau ( 2019-08-21 08:10:14 +0200 )edit

Thank you very much!

Vochau gravatar imageVochau ( 2019-08-21 11:25:44 +0200 )edit

@Vochau I would suggest not simply copy/pasting. Try to type out the code that @rburing wrote manually and make sure, step by step, that you understand what it's doing. That way you'll be able to learn more, and be able to make your own modifications to solve variants of the problem.

Iguananaut gravatar imageIguananaut ( 2019-08-21 11:29:26 +0200 )edit

@rburing Do you study on the Steenrod algebra? I look forward to cooperating with you to write an article. I need the support of the software Sagemath.

Vochau gravatar imageVochau ( 2019-08-21 11:33:57 +0200 )edit

@Vochau I do not study it, but you can write me an e-mail (see my profile/website).

rburing gravatar imagerburing ( 2019-08-21 12:14:31 +0200 )edit
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Nonnegative integer partitions can be obtained using IntegerVectors(n, k) in Sage.

mwageringel gravatar imagemwageringel ( 2019-08-21 19:55:26 +0200 )edit

@rburing Here, there is a question on the Steenrod Algebra: https://ask.sagemath.org/question/365... I am also studying this problem. Can you calculate it in Sage? My Email: vochau150488@gmail.com

Vochau gravatar imageVochau ( 2019-09-22 14:12:35 +0200 )edit
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Asked: 2019-08-19 15:27:56 +0200

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Last updated: Aug 21 '19

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