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Reference documentation for older polymake versions: release 3.4, release 3.3, release 3.2
application group
The application group provides basic functionality for working with permutation groups. An object of type Group
records the abstract properties of the groups that do not depend on any particular representation, such as ORDER, CHARACTER_TABLE and CONJUGACY_CLASS_SIZES. Moreover, it can contain several subobjects of type PermutationAction
, PermutationActionOnSets
or ImplicitActionOnSets
that encode representations of the group. (We use the terms action and representation interchangeably). If the group object is not contained inside a Cone
or Polytope
, the representation in question is encoded as a PERMUTATION_ACTION
, SET_ACTION
or IMPLICIT_SET_ACTION
, otherwise it may be encoded more specifically as a RAY_ACTION, FACET_ACTION, COORDINATE_ACTION, etc. Different representations of the same group are convertible among each other either via specific rules, or by using the function induced_action
, for example.
imports from:
 application common
Objects
Action
:
parametrized object used for encoding group actions (representations). GeneratorType is
Array<Int>
for permutation groups, orMatrix<Scalar>
for matrix groups.
 DomainType is
Int
for permutation groups,Vector<Scalar>
for matrix groups acting on facets or vertices,Set<Int>
orBitset
for groups acting on simplices,IncidenceMatrix
for groups acting on (maximal) cones of a fan
 OrbitGeneratorScalarType is the type of the entries of vectors that generate a geometric orbit; default
Rational
Group
:
Object encoding a finite group.ImplicitActionOnSets
:
derived object encoding an action of a permutation group on a collection of sets, but where only one representative of each orbit is stored explicitlyLayeredPermutationAction
:
object for encoding the separate actions of a group on a collection of sets, induced by the same generatorsMatrixActionOnVectors
:
derived object for matrix groupsPermutationAction
:
derived objects for permutation representationsPermutationActionOnSets
:
derived object for permuting collections of sets
Functions
Orbits
These functions are concerned with orbits in groups.

are_in_same_orbit(PermutationAction a, Vector v1, Vector v2)
Checks whether vectors v1 and v2 are in the same orbit with respect to the (coordinate) action of group.
 Parameters:
PermutationAction
a
: the permutation group acting on coordinatesVector
v1
Vector
v2
 Returns:

orbit<action_type>(Array G, Any O)
The orbit of an object O under a group generated by G. The action_type defines how the elements of the group work on O.
 Type Parameters:
action_type
: controls theon_container
the default. The group acts on the elements of a given container, which also could be container.on_elements
for this the group will act on the deepest elements inside a given container with respect to the type of the group elementson_rows
For this O should be a matrix so that the group can act on the rows of O.on_cols
likeon_rows
this require a matrix so that the group can act on its columnson_nonhomog_cols
also require that O is a matrix on whose columns the group generated by G acts. The 0th column stay fixed. Parameters:
Array
G
: Group generatorsAny
O
: (mostly Array, Vector, Matrix or Set) Returns:
Set<Any>
 Example:
> $permutationgroup = new Array<Array<Int>>([[1,2,3,0]]); > $set = new Set<Set<Int>>([[0,1],[2,3]]); > print orbit<on_elements>($permutationgroup, $set); {{{0 1} {2 3}} {{0 3} {1 2}}}

orbit<action_type>(Group G, Any C)
The orbit of a container C under a group G.
 Type Parameters:
action_type
: by defaulton_container
can also beon_elements
,on_rows
,on_cols
oron_nonhomog_cols
. Call help “<action_type>”; for more information about this. Parameters:
Group
G
Any
C
 Returns:
Set<Any>

orbit<Scalar>(Array<Matrix<Scalar>> G, Vector<Scalar> V)
The orbit of a vector V under a group generated by G.
 Type Parameters:
Scalar
: S the number type Parameters:
Vector<Scalar>
V
 Returns:

orbit_permlib(PermutationAction G, Set S)
The orbit of a set S under a group defined by G.

orbit_permlib(PermutationAction G, Set<Set> S)
The orbit of a set S of sets under a group given by G.

orbit_representatives(Array<GeneratorType> G)
The indices of one representative for each orbit under the group generated by G.
 Parameters:
Array<GeneratorType>
G
: Group generators Returns:

orbits_in_orbit_order(PermutationAction a, Matrix M)
Computes the orbit of the rows of the matrix mat under the permutation action on coordinates action.
 Parameters:
PermutationAction
a
: an action of a group of coordinate permutationsMatrix
M
: some input vectors Returns:

orbits_of_action(PermutationAction a)
Computes the orbits of the basic set under a.
 Parameters:
PermutationAction
a
: a permutation action of a group Returns:

orbits_of_coordinate_action(PermutationAction a, Matrix<Scalar> M)
Computes the orbits of the vectors (homogenized) of the rows of a matrix M by permuting the coordinates of the vectors (skipping the homogenizing coordinate). The group must act on the set of vectors, and the rows of the matrix must contain the entire orbit.
 Parameters:
PermutationAction
a
: an action of a group acting by permuting the coordinatesMatrix<Scalar>
M
: a matrix on whose columns the group acts by coordinate permutation Returns:

orbits_of_induced_action(PermutationAction a, IncidenceMatrix I)
Computes the orbits of a set on which an action is induced. The incidences between the domain elements and the elements in the set are given by an incidence matrix inc.
 Parameters:
PermutationAction
a
: an action of a groupIncidenceMatrix
I
: the incidences between domain elements and elements on which an action is induced Returns:
Producing a group
With these clients you can produce objects of type Group
– groups from certain parameterized families, as stabilizers of sets in other groups or from different kinds of cycle notations.

alternating_group(Int d)
Constructs an alternating group of given degree d.
 Parameters:
Int
d
: degree of the alternating group Returns:

cube_group(Int d)
Constructs the symmetry group of a dcube, acting on vertices, for 1 ⇐ d ⇐ 6 (for the moment), along with the corresponding character table and conjugacy class representatives.

cyclic_group(Int d)
Constructs a cyclic group of given degree d.
 Parameters:
Int
d
: degree of the cyclic group Returns:

dihedral_group(Int o)
Constructs a dihedral group of a given order o. If the order is 2, 4, 6, 8, 10, 12, 16, 20 or 24, the character table is exact, otherwise some entries are mutilated rational approximations of algebraic numbers.
 Parameters:
Int
o
: order of the dihedral group that acts on a regular (o/2)gon Returns:

group_from_cyclic_notation0(String generators)
Constructs a group from a string with generators in cyclic notation. All numbers in the string are 0based. Example: “(0,2)(1,3)”

group_from_cyclic_notation1(String generators)
Constructs a group from a string with generators in cyclic notation. All numbers in the string are 1based.

group_from_permlib_cyclic_notation(Array<String> gens, Int degree)
Constructs a Group from generators given in permlib cyclic notation, i.e., indices separated by whitespace, generators separated by commas.
 Parameters:
Int
degree
: the degree of the permutation group Returns:

stabilizer_of_set(PermutationAction a, Set S)
Computes the subgroup of group which stabilizes the given set of indices set.
 Parameters:
PermutationAction
a
: the action of a permutation groupSet
S
: the set to be stabilized Returns:

stabilizer_of_vector(PermutationAction a, Vector v)
Computes the subgroup of G which stabilizes the given vector v.
 Parameters:
PermutationAction
a
: the action of a permutation groupVector
v
: the vector to be stabilized Returns:

symmetric_group(Int d)
Constructs a symmetric group of given degree d.
 Parameters:
Int
d
: degree of the symmetric group Returns:
Symmetry
These functions are dealing with symmetries.

all_group_elements<Scalar>(MatrixActionOnVectors<Scalar> action)
Compute all elements of a given group, expressed as a matrix group action.
 Type Parameters:
Scalar
: S the underlying number type Parameters:
MatrixActionOnVectors<Scalar>
action
: the action of a permutation group Returns:
 Example:
To generate all elements of the regular representation of S_3, type
> print all_group_elements(symmetric_group(3)>REGULAR_REPRESENTATION); <0 0 1 0 1 0 1 0 0 > <0 0 1 1 0 0 0 1 0 > <0 1 0 0 0 1 1 0 0 > <0 1 0 1 0 0 0 0 1 > <1 0 0 0 0 1 0 1 0 > <1 0 0 0 1 0 0 0 1 >

automorphism_group(GraphAdjacency graph)
Find the automorphism group of the graph.
 Parameters:
GraphAdjacency
graph
 Returns:

automorphism_group(IncidenceMatrix I, Bool on_rows)
Find the automorphism group of the incidence matrix.
 Parameters:
Bool
on_rows
: true (default) for row action Returns:

col_to_row_action(Matrix M, Array<Array> p)
If the action of some permutations on the entries of the rows maps each row of a matrix to another row we obtain an induced action on the set of rows of the matrix. Considering the rows as points this corresponds to the action on the points induced by the action of some permutations on the coordinates.
 Parameters:
Matrix
M
 Returns:

conjugacy_class<Element>(Action action, Element e)
Compute the conjugacy class of a group element under a given action

conjugacy_class<Scalar>(MatrixActionOnVectors<Scalar> action, Matrix<Scalar> e)
Compute the conjugacy class of a group element under a given action
 Type Parameters:
Scalar
: E the underlying number type Parameters:
MatrixActionOnVectors<Scalar>
action
: the action of the groupMatrix<Scalar>
e
: the element to be acted upon Returns:

group_left_multiplication_table(Group G)
Calculate the left multiplication table of a group action, in which GMT[g][h] = hg

group_right_multiplication_table(Group G)
Calculate the right multiplication table of a group action, in which GMT[g][h] = gh

implicit_character(ImplicitActionOnSets A)
Calculate character of an implicit action
 Parameters:
ImplicitActionOnSets
A
: the given action Returns:

induce_implicit_action(PermutationAction original_action, String property)
Construct an implicit action of the action induced on a collection of sets. Only a set of orbit representatives is stored, not the full induced action.
 Parameters:
PermutationAction
original_action
: the action of the group on indicesString
property
: the name of a property that describes an ordered list of sets on which the group should act Returns:
 Example:
To construct the implicit action of the symmetry group of a cube on its maximal simplices, type:
> $c=cube(3, group=>1, character_table=>0); > group::induce_implicit_action($c, $c>GROUP>VERTICES_ACTION, $c>GROUP>REPRESENTATIVE_MAX_INTERIOR_SIMPLICES, "MAX_INTERIOR_SIMPLICES")>properties(); name: induced_implicit_action_of_ray_action_on_MAX_INTERIOR_SIMPLICES type: ImplicitActionOnSets description: induced from ray_action on MAX_INTERIOR_SIMPLICES DOMAIN_NAME MAX_INTERIOR_SIMPLICES EXPLICIT_ORBIT_REPRESENTATIVES {0 1 2 4} {0 1 2 5} {0 1 2 7} {0 3 5 6} GENERATORS 1 0 3 2 5 4 7 6 0 2 1 3 4 6 5 7 0 1 4 5 2 3 6 7

induce_set_action(Cone c, PermutationAction a, String domain)
Construct the induced action of a permutation action on a property that is an ordered collection of sets, such as MAX_INTERIOR_SIMPLICES.
 Parameters:
Cone
c
: the cone or polytopePermutationAction
a
: a permutation action on, for example, the vertex indicesString
domain
: the property the induced action should act upon Returns:
 Example:
> $c=cube(3, group=>1, character_table=>0); > group::induce_set_action($c, $c>GROUP>VERTICES_ACTION, "MAX_INTERIOR_SIMPLICES")>properties(); name: induced_set_action_of_ray_action_on_MAX_INTERIOR_SIMPLICES type: PermutationActionOnSets description: induced from ray_action on MAX_INTERIOR_SIMPLICES DOMAIN_NAME MAX_INTERIOR_SIMPLICES GENERATORS 5 4 7 6 1 0 3 2 11 10 9 8 30 29 32 31 38 40 39 41 33 36 35 34 37 43 42 45 44 13 12 15 14 20 23 22 21 24 16 18 17 19 26 25 28 27 49 48 47 46 55 54 57 56 51 50 53 52 0 2 1 3 12 14 13 15 16 17 18 19 4 6 5 7 8 9 10 11 21 20 22 24 23 25 27 26 28 29 31 30 32 34 33 35 37 36 46 47 48 49 50 52 51 53 38 39 40 41 42 44 43 45 54 56 55 57 0 4 8 9 1 5 10 11 2 3 6 7 16 20 25 26 12 17 21 27 13 18 22 23 28 14 15 19 24 33 38 42 43 29 34 35 39 44 30 36 40 45 31 32 37 41 50 51 54 55 46 47 52 56 48 49 53 57

induced_action(PermutationAction a, Array<Set<Int>> domain)
Given a permutation action a on some indices and an ordered list domain of sets containing these indices, we ask for the permutation action induced by a on this list of sets.
 Parameters:
PermutationAction
a
: a permutation action that acts on some indices Returns:
 Example:
Consider the symmetry group of the 3cube acting on vertices, and induce from it the action on the facets:
> $a = cube_group(3)>PERMUTATION_ACTION; > $f = new Array<Set>([[0,2,4,6],[1,3,5,7],[0,1,4,5],[2,3,6,7],[0,1,2,3],[4,5,6,7]]); > print $a>GENERATORS; 1 0 3 2 5 4 7 6 0 2 1 3 4 6 5 7 0 1 4 5 2 3 6 7
> print induced_action($a,$f)>GENERATORS; 1 0 2 3 4 5 2 3 0 1 4 5 0 1 4 5 2 3
 Example:
To see what the permutation [0,2,1] induces on the array [{0,1},{0,2}], do the following:
> $a = new Array<Set<Int>>(2); > $a>[0] = new Set<Int>(0,1); > $a>[1] = new Set<Int>(0,2); > $p = new PermutationAction(GENERATORS=>[[0,2,1]]); > print induced_action($p,$a)>properties; type: PermutationActionOnSets GENERATORS 1 0

induced_permutations(Array<Array<Int>> gens, Matrix M)
gives the permutations that are induced on the rows of a matrix M by the action of gens on the columns of M

induced_permutations(Array<Matrix<Scalar>> gens, Matrix M)
gives the permutations that are induced on the rows of a matrix M by the action of gens on the columns of M. The matrices in gens define the permutations by multiplicate the rows from the right side on it.
 Parameters:
Matrix
M
: the matrix acted upon Options:
Bool
homogeneous_action
: should the generators also act on the homogeneous column? Default False Returns:
 Example:
> $gens = new Array<Matrix>([new Matrix([[0,1,0],[0,0,1],[1,0,0]]), new Matrix([[0,0,1],[1,0,0],[0,1,0]])]); > $M = new Matrix([[1,2,3],[3,1,2],[2,3,1]]); > print induced_permutations($gens, $M, homogeneous_action=>1); 2 0 1 1 2 0

induced_permutations(Array<Array<Int>> gens, Array<DomainType> S)
gives the permutations that are induced on an ordered collection S by the action of gens on the elements of S
 Parameters:
Array<DomainType>
S
: the collection acted upon Returns:

induced_permutations(Array<Array<Int>> a, IncidenceMatrix M)
gives the permutations that are induced on the rows of an incidence matrix M by the action of gens on the columns of M
 Parameters:
IncidenceMatrix
M
: the matrix acted upon Returns:

induced_permutations_set_set(Array<Array<Int>> gens, Array<Set<Set>> domain)
gives the permutations that are induced on an Array<Set<Set» by permuting the elements of the inner set
 Parameters:
 Returns:

induced_rep(Cone C, PermutationActionOnSets A, Array<Int> g)
Calculate the representation of a group element
 Parameters:
Cone
C
: the cone or polytope containing the sets acted uponPermutationActionOnSets
A
: the action in question Returns:

invariant_polynomials(MatrixActionOnVectors a, Int d)
Given a matrix action a of a group G on some ndimensional vector space and a total degree d, calculate the Ginvariant polynomials of total degree 0 < deg ≤ d in n variables. This is done by calculating the aorbit of all monomials of total degree at most d. By a theorem of Noether, for d = the order of G the output is guaranteed to generate the entire ring of Ginvariant polynomials. No effort is made to calculate a basis of the ideal generated by these invariants.
 Parameters:
MatrixActionOnVectors
a
: the matrix actionInt
d
: the maximal degree of the sought invariants Options:
Bool
action_is_affine
: is the action a affine, ie., ignore the first row and column of the generating matrices? Default yes Example:
To calculate the invariants of degree at most six of the matrix action of the symmetry group of the 3cube, type
> $c = cube(3, group=>1); > print join "\n", @{group::invariant_polynomials($c>GROUP>MATRIX_ACTION, 6)}; x_0^2 + x_1^2 + x_2^2 x_0^2*x_1^2 + x_0^2*x_2^2 + x_1^2*x_2^2 x_0^2*x_1^2*x_2^2 x_0^4 + x_1^4 + x_2^4 x_0^4*x_1^2 + x_0^4*x_2^2 + x_0^2*x_1^4 + x_0^2*x_2^4 + x_1^4*x_2^2 + x_1^2*x_2^4 x_0^6 + x_1^6 + x_2^6

irreducible_decomposition<Scalar>(Vector<Scalar> character, Group G)
Calculate the decomposition into irreducible components of a given representation
 Type Parameters:
Scalar
: the number type of the character Parameters:
Vector<Scalar>
character
: the character of the given representationGroup
G
: the given group; it needs to know its CHARACTER_TABLE and CONJUGACY_CLASS_SIZES. Returns:
 Example:
Remember that in polymake, we use the terms action and representation interchangeably. To calculate the irreducible decomposition of the vertex action of the symmetry group of the 3cube, type
> $g = cube_group(3); $a = $g>PERMUTATION_ACTION; > print irreducible_decomposition($a>CHARACTER, $g); 1 0 0 1 0 0 0 0 1 1
Thus, the action of the symmetry group on the vertices decomposes into one copy of each of the irreducible representations corresponding to the rows 0,3,8,9 of the character table:
> print $g>CHARACTER_TABLE>minor([0,3,8,9],All); 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3 1 0 1 1 1 0 1 1 3 3 1 0 1 1 1 0 1 1 3
The first entries of these rows say that a decomposes into two 1dimensional irreps and two 3dimensional ones. This correctly brings the dimension of the representation a to 8, the number of vertices of the 3cube.

isotypic_basis(Group G, PermutationActionOnSets A, Int i)
Calculate a basis of the isotypic component given by the ith irrep
 Parameters:
Group
G
: the acting group, which needs to know its CHARACTER_TABLEPermutationActionOnSets
A
: the representation in question, which needs to know its corresponding CONJUGACY_CLASSESInt
i
: the index of the sought irrep Options:
Bool
permute_to_orbit_order
: Should the rows and columns be ordered by orbits? Default 1 Returns:
 Example:
Consider the action of the symmetry group of the 3cube on the set of facets:
> $g = cube_group(3); > $f = new Array<Set>([[0,2,4,6],[1,3,5,7],[0,1,4,5],[2,3,6,7],[0,1,2,3],[4,5,6,7]]); > $a = induced_action($g>PERMUTATION_ACTION, $f); > print irreducible_decomposition($a>CHARACTER, $g) 1 0 0 0 0 1 0 0 0 1
Now we can calculate a basis of the 5th irrep:
> print isotypic_basis($g, $a, 5); 1/6 1/6 1/3 1/3 1/6 1/6 1/3 1/3 1/6 1/6 1/6 1/6

isotypic_basis(Group G, PermutationAction A, Int i)
Calculate a basis of the isotypic component given by the ith irrep
 Parameters:
Group
G
: the acting group, which needs to know its CHARACTER_TABLEPermutationAction
A
: the action in question, which needs to know its corresponding CONJUGACY_CLASSESInt
i
: the index of the sought irrep Options:
Bool
permute_to_orbit_order
: Should the rows and columns be ordered by orbits? Default 1 Returns:
 Example:
Consider the action of the symmetry group of the 3cube on its vertices. We first calculate its decomposition into irreducible representations via
> $g = cube_group(3); $a = $g>PERMUTATION_ACTION; > print irreducible_decomposition($a>CHARACTER, $g); 1 0 0 1 0 0 0 0 1 1
We now calculate a basis of the 3rd irrep:
> print isotypic_basis($g,$a,3); 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8

isotypic_basis<Scalar>(Group G, MatrixActionOnVectors<Scalar> A, Int i)
Calculate a basis of the isotypic component given by the ith irrep
 Type Parameters:
Scalar
: S the underlying number type Parameters:
Group
G
: the acting group, which needs to know its CHARACTER_TABLEMatrixActionOnVectors<Scalar>
A
: the matrix action in question, which needs to know its corresponding CONJUGACY_CLASSESInt
i
: the index of the sought irrep Returns:

isotypic_projector(Group G, PermutationAction A, Int i)
Calculate the projection map into the isotypic component given by the ith irrep. The map is given by a block matrix, the rows and columns of which are indexed by the domain elements; by default, these are ordered by orbits.
 Parameters:
Group
G
: the acting groupPermutationAction
A
: the action in questionInt
i
: the index of the sought irrep Options:
Bool
permute_to_orbit_order
: Should the rows and columns be ordered by orbits? Default 1 Returns:
 Example:
Consider the action of the symmetry group of the 3cube on its vertices. We first calculate its decomposition into irreducible representations via
> $g = cube_group(3); $a = $g>PERMUTATION_ACTION; > print irreducible_decomposition($a>CHARACTER, $g); 1 0 0 1 0 0 0 0 1 1
We now calculate the projection matrices to the irreps number 3 and 8:
> $p3 = isotypic_projector($g,$a,3); print $p3, "\n", rank($p3); 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1
> $p8 = isotypic_projector($g,$a,8); print $p8, "\n", rank($p8); 3/8 1/8 1/8 1/8 1/8 1/8 1/8 3/8 1/8 3/8 1/8 1/8 1/8 1/8 3/8 1/8 1/8 1/8 3/8 1/8 1/8 3/8 1/8 1/8 1/8 1/8 1/8 3/8 3/8 1/8 1/8 1/8 1/8 1/8 1/8 3/8 3/8 1/8 1/8 1/8 1/8 1/8 3/8 1/8 1/8 3/8 1/8 1/8 1/8 3/8 1/8 1/8 1/8 1/8 3/8 1/8 3/8 1/8 1/8 1/8 1/8 1/8 1/8 3/8 3
From this we deduce that the irrep indexed 3 has dimension 1, and the one indexed 8 has dimension 3. This is consistent with the information collected in the character table:
> print $g>CHARACTER_TABLE>minor([3,8],All); 1 1 1 1 1 1 1 1 1 1 3 1 0 1 1 1 0 1 1 3
In effect, the first entries in these rows are 1 and 3, respectively.

isotypic_projector<Scalar>(Group G, MatrixActionOnVectors<Scalar> A, Int i)
Calculate the projection map into the isotypic component given by the ith irrep. Note that the option permute_to_orbit_order makes no sense for matrix actions, so it is always set to 0.
 Type Parameters:
Scalar
: S the underlying number type Parameters:
Group
G
: the acting groupMatrixActionOnVectors<Scalar>
A
: the action in questionInt
i
: the index of the sought irrep Returns:
 Example:
We first construct a matrix action:
> $s = symmetric_group(3); $a = $s>REGULAR_REPRESENTATION; > print irreducible_decomposition($a>CHARACTER, $s); 0 1 1
Since we now know that the irreps indexed 1 and 2 appear in the regular representation, we project to one of them:
> print isotypic_projector($s, $a, 1); 2/3 1/3 1/3 1/3 2/3 1/3 1/3 1/3 2/3

isotypic_supports(PermutationActionOnSets a, Array<Set> A)
For each isotypic component of a representation a, which of a given array A of sets are supported on it?
 Parameters:
PermutationActionOnSets
a
: the representation in question Options:
Bool
permute_to_orbit_order
: Should the columns be ordered by orbits? Default 1 Returns:

isotypic_supports(PermutationActionOnSets a, SparseMatrix M)
For each row of a given SparseMatrix M, to which isotypic components of a representation a does it have a nonzero projection? The columns of the SparseMatrix correspond, in order, to the sets of the representation.
 Parameters:
PermutationActionOnSets
a
: the representation in questionSparseMatrix
M
: the given matrix Options:
Bool
permute_to_orbit_order
: Should the columns be ordered by orbits? Default 1 Returns:

lex_min_representative(Group G, Set S)
Computes the lexicographically smallest representative of a given set with respect to a group

orbit_reps_and_sizes<Container>(Array<Array<Int>> generators, Container S)
Computes the lexicographically smallest representatives of a given array of sets with respect to a group, along with the corresponding orbit sizes
 Type Parameters:
Container
: a container of sets, for example Array<Set> or IncidenceMatrix Parameters:
Container
S
: a container of sets, for example Array<Set> or IncidenceMatrix Returns:
 Example:
To calculate the orbits and orbit sizes of an icosidodecahedron, type
> $q=polytope::icosidodecahedron(); > print orbit_reps_and_sizes($q>GROUP>VERTICES_ACTION>GENERATORS,$q>VERTICES_IN_FACETS); <{0 1 2 4 6} {0 1 3} > 12 20

partition_representatives(Array<Array<Int>> gens, Set<Int> S)
Partition a group into translates of a set stabilizer
 Parameters:
 Returns:

regular_representation(PermutationAction a)
Calculate the regular representation of a permutation action
 Parameters:
PermutationAction
a
: a permutation action Returns:
 Example:
To calculate the regular representation of the symmetric group S_3, type
> $s = symmetric_group(3); $s>REGULAR_REPRESENTATION; > print $s>REGULAR_REPRESENTATION>properties(); type: MatrixActionOnVectors<Rational> CONJUGACY_CLASS_REPRESENTATIVES <1 0 0 0 1 0 0 0 1 > <0 1 0 1 0 0 0 0 1 > <0 0 1 1 0 0 0 1 0 > GENERATORS <0 1 0 1 0 0 0 0 1 > <1 0 0 0 0 1 0 1 0 >

row_support_sizes(SparseMatrix M)
How many nonzero entries are there in each row of a SparseMatrix?
 Parameters:
SparseMatrix
M
: the given matrix Returns:

span_same_subspace(Array<HashMap<SetType,Rational>> S1, Array<HashMap<SetType,Rational>> S2)
Do two collections S1, S2 of sparse vectors span the same subspace?
 Parameters:
 Returns:

spans_invariant_subspace(ImplicitActionOnSets a, Array<HashMap<Bitset,Rational>> S)
Does a set S of sparse vectors span an invariant subspace under an implicit group action a?
 Parameters:
ImplicitActionOnSets
a
: the given action Options:
Bool
verbose
: give a certificate if the answer is False Returns:

sparse_isotypic_basis(PermutationActionOnSets rep, Int i)
Calculate a sparse representation of a basis for an isotypic component. For this, the sets in the representation are listed in order by orbit. In this basis, the projection matrix to the isotypic component decomposes into blocks, one for each orbit.
 Parameters:
PermutationActionOnSets
rep
: the given representationInt
i
: the index of the irrep that defines the isotypic component Options:
Bool
use_double
: use inexact arithmetic for reducing the basis; default 0String
filename
: if defined, the basis will be written to a file with this name, but not returned. Use this option if you expect very large output. Returns:

sparse_isotypic_spanning_set(PermutationActionOnSets rep, Int i)
Calculate a sparse representation of a spanning set for an isotypic component. For this, the sets in the representation are listed in order by orbit. In this basis, the projection matrix to the isotypic component decomposes into blocks, one for each orbit.
 Parameters:
PermutationActionOnSets
rep
: the given representationInt
i
: the index of the irrep that defines the isotypic component Options:
String
filename
: if defined, the basis will be written to a file with this name, but not returned. Use this option if you expect very large output. Returns:

sparse_isotypic_support(PermutationActionOnSets rep, Int i)
Calculate the support of a sparse representation of a spanning set for an isotypic component.
 Parameters:
PermutationActionOnSets
rep
: the given representationInt
i
: the index of the irrep that defines the isotypic component Options:
String
filename
: if defined, the basis will be written to a file with this name, but not returned. Use this option if you expect very large output. Bool equivalence_class_only only report representatives of simplices, default true
 Bool index_only only output the indices of the representatives to filename, default true
 Returns:
Utilities
Miscellaneous functions.

action<action_type>(Any g, Any O)
The image of an object O under a group element g. The action_type defines how g acts on O. For more information see the help function on the action types.
 Type Parameters:
action_type
: must be compatible with O by defaulton_container
can also beon_elements
,on_rows
,on_cols
,on_nonhomog_cols
 Parameters:
Any
g
: Group elementAny
O
: Container type like Array, Set, Matrix or Vector Returns:
Any
 Example:
> $g = new Array<Int>([1,2,0]); > $O = new Matrix<Int>([[0,0],[1,1],[2,2]]); > print $O; 0 0 1 1 2 2
> print action<on_rows>($g, $O); 1 1 2 2 0 0

action_from_generators(Array<Array<Int>> gens, Group action)
Computes groups with a permutation action with the basic properties BASE, STRONG_GENERATORS, and TRANSVERSALS.
 Parameters:
Group
action
: the generated action

action_inv<action_type>(Array<Int> p, Any O)
The image of an object O under the inverse of a permutation p. The way it acts on O is given by the action_type.
 Type Parameters:
action_type
: must be compatible with O, by defaulton_container
can also beon_elements
,on_rows
,on_cols
oron_nonhomog_cols
 Parameters:
Any
O
: Container type like Array, Set, Matrix or Vector Returns:
Any
 Example:
> $p = new Array<Int>([1,2,0]); > $O = new Array<Int>([2,3,1]); > print action_inv($p,$O); 1 2 3

action_to_cyclic_notation(PermutationAction a)
Returns group generators in 1based cyclic notation (GAP like, not permlib like notation)
 Parameters:
PermutationAction
a
: the action of the permutation group Returns:

all_group_elements(PermutationAction a)
Compute all elements of a given group, expressed as a permutation action.
 Parameters:
PermutationAction
a
: the action of a permutation group Returns: