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Identifier
Values
=>
Cc0005;cc-rep
[1,0]=>0 [1,0,1,0]=>0 [1,1,0,0]=>1 [1,0,1,0,1,0]=>0 [1,0,1,1,0,0]=>1 [1,1,0,0,1,0]=>1 [1,1,0,1,0,0]=>1 [1,1,1,0,0,0]=>1 [1,0,1,0,1,0,1,0]=>0 [1,0,1,0,1,1,0,0]=>1 [1,0,1,1,0,0,1,0]=>1 [1,0,1,1,0,1,0,0]=>1 [1,0,1,1,1,0,0,0]=>1 [1,1,0,0,1,0,1,0]=>1 [1,1,0,0,1,1,0,0]=>2 [1,1,0,1,0,0,1,0]=>1 [1,1,0,1,0,1,0,0]=>2 [1,1,0,1,1,0,0,0]=>2 [1,1,1,0,0,0,1,0]=>1 [1,1,1,0,0,1,0,0]=>2 [1,1,1,0,1,0,0,0]=>1 [1,1,1,1,0,0,0,0]=>2 [1,0,1,0,1,0,1,0,1,0]=>0 [1,0,1,0,1,0,1,1,0,0]=>1 [1,0,1,0,1,1,0,0,1,0]=>1 [1,0,1,0,1,1,0,1,0,0]=>1 [1,0,1,0,1,1,1,0,0,0]=>1 [1,0,1,1,0,0,1,0,1,0]=>1 [1,0,1,1,0,0,1,1,0,0]=>2 [1,0,1,1,0,1,0,0,1,0]=>1 [1,0,1,1,0,1,0,1,0,0]=>2 [1,0,1,1,0,1,1,0,0,0]=>2 [1,0,1,1,1,0,0,0,1,0]=>1 [1,0,1,1,1,0,0,1,0,0]=>2 [1,0,1,1,1,0,1,0,0,0]=>1 [1,0,1,1,1,1,0,0,0,0]=>2 [1,1,0,0,1,0,1,0,1,0]=>1 [1,1,0,0,1,0,1,1,0,0]=>2 [1,1,0,0,1,1,0,0,1,0]=>2 [1,1,0,0,1,1,0,1,0,0]=>2 [1,1,0,0,1,1,1,0,0,0]=>2 [1,1,0,1,0,0,1,0,1,0]=>1 [1,1,0,1,0,0,1,1,0,0]=>2 [1,1,0,1,0,1,0,0,1,0]=>2 [1,1,0,1,0,1,0,1,0,0]=>2 [1,1,0,1,0,1,1,0,0,0]=>2 [1,1,0,1,1,0,0,0,1,0]=>2 [1,1,0,1,1,0,0,1,0,0]=>2 [1,1,0,1,1,0,1,0,0,0]=>2 [1,1,0,1,1,1,0,0,0,0]=>2 [1,1,1,0,0,0,1,0,1,0]=>1 [1,1,1,0,0,0,1,1,0,0]=>2 [1,1,1,0,0,1,0,0,1,0]=>2 [1,1,1,0,0,1,0,1,0,0]=>2 [1,1,1,0,0,1,1,0,0,0]=>2 [1,1,1,0,1,0,0,0,1,0]=>1 [1,1,1,0,1,0,0,1,0,0]=>2 [1,1,1,0,1,0,1,0,0,0]=>2 [1,1,1,0,1,1,0,0,0,0]=>2 [1,1,1,1,0,0,0,0,1,0]=>2 [1,1,1,1,0,0,0,1,0,0]=>2 [1,1,1,1,0,0,1,0,0,0]=>2 [1,1,1,1,0,1,0,0,0,0]=>2 [1,1,1,1,1,0,0,0,0,0]=>2 [1,0,1,0,1,0,1,0,1,0,1,0]=>0 [1,0,1,0,1,0,1,0,1,1,0,0]=>1 [1,0,1,0,1,0,1,1,0,0,1,0]=>1 [1,0,1,0,1,0,1,1,0,1,0,0]=>1 [1,0,1,0,1,0,1,1,1,0,0,0]=>1 [1,0,1,0,1,1,0,0,1,0,1,0]=>1 [1,0,1,0,1,1,0,0,1,1,0,0]=>2 [1,0,1,0,1,1,0,1,0,0,1,0]=>1 [1,0,1,0,1,1,0,1,0,1,0,0]=>2 [1,0,1,0,1,1,0,1,1,0,0,0]=>2 [1,0,1,0,1,1,1,0,0,0,1,0]=>1 [1,0,1,0,1,1,1,0,0,1,0,0]=>2 [1,0,1,0,1,1,1,0,1,0,0,0]=>1 [1,0,1,0,1,1,1,1,0,0,0,0]=>2 [1,0,1,1,0,0,1,0,1,0,1,0]=>1 [1,0,1,1,0,0,1,0,1,1,0,0]=>2 [1,0,1,1,0,0,1,1,0,0,1,0]=>2 [1,0,1,1,0,0,1,1,0,1,0,0]=>2 [1,0,1,1,0,0,1,1,1,0,0,0]=>2 [1,0,1,1,0,1,0,0,1,0,1,0]=>1 [1,0,1,1,0,1,0,0,1,1,0,0]=>2 [1,0,1,1,0,1,0,1,0,0,1,0]=>2 [1,0,1,1,0,1,0,1,0,1,0,0]=>2 [1,0,1,1,0,1,0,1,1,0,0,0]=>2 [1,0,1,1,0,1,1,0,0,0,1,0]=>2 [1,0,1,1,0,1,1,0,0,1,0,0]=>2 [1,0,1,1,0,1,1,0,1,0,0,0]=>2 [1,0,1,1,0,1,1,1,0,0,0,0]=>2 [1,0,1,1,1,0,0,0,1,0,1,0]=>1 [1,0,1,1,1,0,0,0,1,1,0,0]=>2 [1,0,1,1,1,0,0,1,0,0,1,0]=>2 [1,0,1,1,1,0,0,1,0,1,0,0]=>2 [1,0,1,1,1,0,0,1,1,0,0,0]=>2 [1,0,1,1,1,0,1,0,0,0,1,0]=>1 [1,0,1,1,1,0,1,0,0,1,0,0]=>2 [1,0,1,1,1,0,1,0,1,0,0,0]=>2 [1,0,1,1,1,0,1,1,0,0,0,0]=>2 [1,0,1,1,1,1,0,0,0,0,1,0]=>2 [1,0,1,1,1,1,0,0,0,1,0,0]=>2 [1,0,1,1,1,1,0,0,1,0,0,0]=>2 [1,0,1,1,1,1,0,1,0,0,0,0]=>2 [1,0,1,1,1,1,1,0,0,0,0,0]=>2 [1,1,0,0,1,0,1,0,1,0,1,0]=>1 [1,1,0,0,1,0,1,0,1,1,0,0]=>2 [1,1,0,0,1,0,1,1,0,0,1,0]=>2 [1,1,0,0,1,0,1,1,0,1,0,0]=>2 [1,1,0,0,1,0,1,1,1,0,0,0]=>2 [1,1,0,0,1,1,0,0,1,0,1,0]=>2 [1,1,0,0,1,1,0,0,1,1,0,0]=>3 [1,1,0,0,1,1,0,1,0,0,1,0]=>2 [1,1,0,0,1,1,0,1,0,1,0,0]=>3 [1,1,0,0,1,1,0,1,1,0,0,0]=>3 [1,1,0,0,1,1,1,0,0,0,1,0]=>2 [1,1,0,0,1,1,1,0,0,1,0,0]=>3 [1,1,0,0,1,1,1,0,1,0,0,0]=>2 [1,1,0,0,1,1,1,1,0,0,0,0]=>3 [1,1,0,1,0,0,1,0,1,0,1,0]=>1 [1,1,0,1,0,0,1,0,1,1,0,0]=>2 [1,1,0,1,0,0,1,1,0,0,1,0]=>2 [1,1,0,1,0,0,1,1,0,1,0,0]=>2 [1,1,0,1,0,0,1,1,1,0,0,0]=>2 [1,1,0,1,0,1,0,0,1,0,1,0]=>2 [1,1,0,1,0,1,0,0,1,1,0,0]=>3 [1,1,0,1,0,1,0,1,0,0,1,0]=>2 [1,1,0,1,0,1,0,1,0,1,0,0]=>3 [1,1,0,1,0,1,0,1,1,0,0,0]=>3 [1,1,0,1,0,1,1,0,0,0,1,0]=>2 [1,1,0,1,0,1,1,0,0,1,0,0]=>3 [1,1,0,1,0,1,1,0,1,0,0,0]=>2 [1,1,0,1,0,1,1,1,0,0,0,0]=>3 [1,1,0,1,1,0,0,0,1,0,1,0]=>2 [1,1,0,1,1,0,0,0,1,1,0,0]=>3 [1,1,0,1,1,0,0,1,0,0,1,0]=>2 [1,1,0,1,1,0,0,1,0,1,0,0]=>3 [1,1,0,1,1,0,0,1,1,0,0,0]=>3 [1,1,0,1,1,0,1,0,0,0,1,0]=>2 [1,1,0,1,1,0,1,0,0,1,0,0]=>3 [1,1,0,1,1,0,1,0,1,0,0,0]=>2 [1,1,0,1,1,0,1,1,0,0,0,0]=>3 [1,1,0,1,1,1,0,0,0,0,1,0]=>2 [1,1,0,1,1,1,0,0,0,1,0,0]=>3 [1,1,0,1,1,1,0,0,1,0,0,0]=>2 [1,1,0,1,1,1,0,1,0,0,0,0]=>3 [1,1,0,1,1,1,1,0,0,0,0,0]=>3 [1,1,1,0,0,0,1,0,1,0,1,0]=>1 [1,1,1,0,0,0,1,0,1,1,0,0]=>2 [1,1,1,0,0,0,1,1,0,0,1,0]=>2 [1,1,1,0,0,0,1,1,0,1,0,0]=>2 [1,1,1,0,0,0,1,1,1,0,0,0]=>2 [1,1,1,0,0,1,0,0,1,0,1,0]=>2 [1,1,1,0,0,1,0,0,1,1,0,0]=>3 [1,1,1,0,0,1,0,1,0,0,1,0]=>2 [1,1,1,0,0,1,0,1,0,1,0,0]=>3 [1,1,1,0,0,1,0,1,1,0,0,0]=>3 [1,1,1,0,0,1,1,0,0,0,1,0]=>2 [1,1,1,0,0,1,1,0,0,1,0,0]=>3 [1,1,1,0,0,1,1,0,1,0,0,0]=>2 [1,1,1,0,0,1,1,1,0,0,0,0]=>3 [1,1,1,0,1,0,0,0,1,0,1,0]=>1 [1,1,1,0,1,0,0,0,1,1,0,0]=>2 [1,1,1,0,1,0,0,1,0,0,1,0]=>2 [1,1,1,0,1,0,0,1,0,1,0,0]=>2 [1,1,1,0,1,0,0,1,1,0,0,0]=>2 [1,1,1,0,1,0,1,0,0,0,1,0]=>2 [1,1,1,0,1,0,1,0,0,1,0,0]=>2 [1,1,1,0,1,0,1,0,1,0,0,0]=>3 [1,1,1,0,1,0,1,1,0,0,0,0]=>2 [1,1,1,0,1,1,0,0,0,0,1,0]=>2 [1,1,1,0,1,1,0,0,0,1,0,0]=>2 [1,1,1,0,1,1,0,0,1,0,0,0]=>2 [1,1,1,0,1,1,0,1,0,0,0,0]=>3 [1,1,1,0,1,1,1,0,0,0,0,0]=>2 [1,1,1,1,0,0,0,0,1,0,1,0]=>2 [1,1,1,1,0,0,0,0,1,1,0,0]=>3 [1,1,1,1,0,0,0,1,0,0,1,0]=>2 [1,1,1,1,0,0,0,1,0,1,0,0]=>3 [1,1,1,1,0,0,0,1,1,0,0,0]=>3 [1,1,1,1,0,0,1,0,0,0,1,0]=>2 [1,1,1,1,0,0,1,0,0,1,0,0]=>3 [1,1,1,1,0,0,1,0,1,0,0,0]=>2 [1,1,1,1,0,0,1,1,0,0,0,0]=>3 [1,1,1,1,0,1,0,0,0,0,1,0]=>2 [1,1,1,1,0,1,0,0,0,1,0,0]=>3 [1,1,1,1,0,1,0,0,1,0,0,0]=>3 [1,1,1,1,0,1,0,1,0,0,0,0]=>3 [1,1,1,1,0,1,1,0,0,0,0,0]=>3 [1,1,1,1,1,0,0,0,0,0,1,0]=>2 [1,1,1,1,1,0,0,0,0,1,0,0]=>3 [1,1,1,1,1,0,0,0,1,0,0,0]=>2 [1,1,1,1,1,0,0,1,0,0,0,0]=>3 [1,1,1,1,1,0,1,0,0,0,0,0]=>2 [1,1,1,1,1,1,0,0,0,0,0,0]=>3
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Description
Half the rank of the matrix $C^T-C$, where $C$ is the Coxeter matrix of the linear Nakayama algebra corresponding to a Dyck path.
If $A$ is a finite-dimensional algebra of finite global dimension with Cartan matrix $C_A$, then the Coxeter matrix of $A$ is $-C_A^{-1}C_A^T$.
The correspondence between linear Nakayama algebras and Dyck paths is explained on the Nakayama algebras page.
Code
gap('LoadPackage("QPA");')

import tempfile as _tf, os as _os
_gap_code = r"""
DeclareOperation("radicalmathelp",[IsList]);

InstallMethod(radicalmathelp, "for a representation of a quiver", [IsList],0,function(LIST)
    local A, GG, M, W, i, projA;
    A := LIST[1];
    M := LIST[2];
    projA := IndecProjectiveModules(A);
    GG := [];
    for i in projA do Append(GG,[RadicalOfModule(i)]);
    od;
    W := [];
    for i in GG do Append(W,[Size(HomOverAlgebra(i,M))]);
    od;
    return(W);
end);

DeclareOperation("radicalmat",[IsList]);

InstallMethod(radicalmat, "for a representation of a quiver", [IsList],0,function(LIST)
    local A, GG, W, g, i, projA;
    A := LIST[1];
    g := GlobalDimensionOfAlgebra(A,33);
    projA := IndecProjectiveModules(A);
    GG := [];
    for i in projA do Append(GG,[RadicalOfModule(i)]);
    od;
    W := [];
    for i in GG do Append(W,[radicalmathelp([A,i])]);
    od;
    return(TransposedMat(W)-W);
end);
"""
with _tf.NamedTemporaryFile(mode="w", suffix=".g", delete=False, dir="/tmp") as _f:
    _f.write('LoadPackage("QPA");;\n')
    _f.write(_gap_code)
    _tmp = _f.name
gap.eval('Read("' + _tmp + '");')
_os.unlink(_tmp)

def kupisch(D):
    DR = D.reverse()
    H = DR.heights()
    return [1 + H[i] for i, s in enumerate(DR) if s == 0] + [1]

def statistic(D):
    K = kupisch(D)
    n = len(K)
    if n <= 1:
        return 0
    A = gap.NakayamaAlgebra(gap.GF(3), K)
    M = gap.radicalmat([A])
    r = gap.eval('RankMat(' + M.name() + ');')
    return ZZ(r) // 2
Created
Jan 05, 2020 at 16:56 by Rene Marczinzik
Updated
Mar 13, 2026 at 14:52 by Nupur Jain