def test_stabilizer():
S = SymmetricGroup(2)
H = S.stabilizer(0)
assert H.generators == [Permutation(1)]
a = Permutation([2, 0, 1, 3, 4, 5])
b = Permutation([2, 1, 3, 4, 5, 0])
G = PermutationGroup([a, b])
G0 = G.stabilizer(0)
assert G0.order() == 60
gens_cube = [[1, 3, 5, 7, 0, 2, 4, 6], [1, 3, 0, 2, 5, 7, 4, 6]]
gens = [Permutation(p) for p in gens_cube]
G = PermutationGroup(gens)
G2 = G.stabilizer(2)
assert G2.order() == 6
G2_1 = G2.stabilizer(1)
v = list(G2_1.generate(af=True))
assert v == [[0, 1, 2, 3, 4, 5, 6, 7], [3, 1, 2, 0, 7, 5, 6, 4]]
gens = (
(1, 2, 0, 4, 5, 3, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19),
(0, 1, 2, 3, 4, 5, 19, 6, 8, 9, 10, 11, 12, 13, 14,
15, 16, 7, 17, 18),
(0, 1, 2, 3, 4, 5, 6, 7, 9, 18, 16, 11, 12, 13, 14, 15, 8, 17, 10, 19))
gens = [Permutation(p) for p in gens]
G = PermutationGroup(gens)
G2 = G.stabilizer(2)
assert G2.order() == 181440
S = SymmetricGroup(3)
assert [G.order() for G in S.basic_stabilizers] == [6, 2]
def test_commutator():
# the commutator of the trivial group and the trivial group is trivial
S = SymmetricGroup(3)
triv = PermutationGroup([Permutation([0, 1, 2])])
assert S.commutator(triv, triv).is_subgroup(triv)
# the commutator of the trivial group and any other group is again trivial
A = AlternatingGroup(3)
assert S.commutator(triv, A).is_subgroup(triv)
# the commutator is commutative
for i in (3, 4, 5):
S = SymmetricGroup(i)
A = AlternatingGroup(i)
D = DihedralGroup(i)
assert S.commutator(A, D).is_subgroup(S.commutator(D, A))
# the commutator of an abelian group is trivial
S = SymmetricGroup(7)
A1 = AbelianGroup(2, 5)
A2 = AbelianGroup(3, 4)
triv = PermutationGroup([Permutation([0, 1, 2, 3, 4, 5, 6])])
assert S.commutator(A1, A1).is_subgroup(triv)
assert S.commutator(A2, A2).is_subgroup(triv)
# examples calculated by hand
S = SymmetricGroup(3)
A = AlternatingGroup(3)
assert S.commutator(A, S).is_subgroup(A)
def test_get_symmetric_group_sgs():
assert get_symmetric_group_sgs(2) == ([0], [Permutation(3)(0, 1)])
assert get_symmetric_group_sgs(2, 1) == ([0], [Permutation(0, 1)(2, 3)])
assert get_symmetric_group_sgs(3) == ([0, 1], [Permutation(4)(0, 1), Permutation(4)(1, 2)])
assert get_symmetric_group_sgs(3, 1) == ([0, 1], [Permutation(0, 1)(3, 4), Permutation(1, 2)(3, 4)])
assert get_symmetric_group_sgs(4) == ([0, 1, 2], [Permutation(5)(0, 1), Permutation(5)(1, 2), Permutation(5)(2, 3)])
assert get_symmetric_group_sgs(4, 1) == ([0, 1, 2], [Permutation(0, 1)(4, 5), Permutation(1, 2)(4, 5), Permutation(2, 3)(4, 5)])
def test_riemann_invariants():
baser, gensr = riemann_bsgs
# R^{d0 d1}_{d1 d0}; ord = [d0,-d0,d1,-d1]; g = [0,2,3,1,4,5]
# T_c = -R^{d0 d1}_{d0 d1}; can = [0,2,1,3,5,4]
g = Permutation([0, 2, 3, 1, 4, 5])
can = canonicalize(g, list(range(2, 4)), 0, (baser, gensr, 1, 0))
assert can == [0, 2, 1, 3, 5, 4]
# use a non minimal BSGS
can = canonicalize(g, list(range(2, 4)), 0, ([2, 0], [Permutation([1, 0, 2, 3, 5, 4]), Permutation([2, 3, 0, 1, 4, 5])], 1, 0))
assert can == [0, 2, 1, 3, 5, 4]
# The following tests in test_riemann_invariants and in
# test_riemann_invariants1 have been checked using xperm.c from XPerm in
# in [1] and with an older version contained in [2]
#
# [1] xperm.c part of xPerm written by J. M. Martin-Garcia
# http://www.xact.es/index.html
# [2] test_xperm.cc in cadabra by Kasper Peeters, http://cadabra.phi-sci.com/
#
# R_d11^d1_d0^d5 * R^{d6 d4 d0}_d5 * R_{d7 d2 d8 d9} *
# R_{d10 d3 d6 d4} * R^{d2 d7 d11}_d1 * R^{d8 d9 d3 d10}
# ord: contravariant d_k ->2*k, covariant d_k -> 2*k+1
# T_c = R^{d0 d1 d2 d3} * R_{d0 d1}^{d4 d5} * R_{d2 d3}^{d6 d7} *
# R_{d4 d5}^{d8 d9} * R_{d6 d7}^{d10 d11} * R_{d8 d9 d10 d11}
g = Permutation([23, 2, 1, 10, 12, 8, 0, 11, 15, 5, 17, 19, 21, 7, 13, 9, 4, 14, 22, 3, 16, 18, 6, 20, 24, 25])
can = canonicalize(g, list(range(24)), 0, (baser, gensr, 6, 0))
assert can == [0, 2, 4, 6, 1, 3, 8, 10, 5, 7, 12, 14, 9, 11, 16, 18, 13, 15, 20, 22, 17, 19, 21, 23, 24, 25]
# use a non minimal BSGS
can = canonicalize(g, list(range(24)), 0, ([2, 0], [Permutation([1, 0, 2, 3, 5, 4]), Permutation([2, 3, 0, 1, 4, 5])], 6, 0))
assert can == [0, 2, 4, 6, 1, 3, 8, 10, 5, 7, 12, 14, 9, 11, 16, 18, 13, 15, 20, 22, 17, 19, 21, 23, 24, 25]
g = Permutation([0, 2, 5, 7, 4, 6, 9, 11, 8, 10, 13, 15, 12, 14, 17, 19, 16, 18, 21, 23, 20, 22, 25, 27, 24, 26, 29, 31, 28, 30, 33, 35, 32, 34, 37, 39, 36, 38, 1, 3, 40, 41])
can = canonicalize(g, list(range(40)), 0, (baser, gensr, 10, 0))
assert can == [0, 2, 4, 6, 1, 3, 8, 10, 5, 7, 12, 14, 9, 11, 16, 18, 13, 15, 20, 22, 17, 19, 24, 26, 21, 23, 28, 30, 25, 27, 32, 34, 29, 31, 36, 38, 33, 35, 37, 39, 40, 41]
def test_check_cycles_alt_sym():
perm1 = Permutation([[0, 1, 2, 3, 4, 5, 6], [7], [8], [9]])
perm2 = Permutation([[0, 1, 2, 3, 4, 5], [6, 7, 8, 9]])
perm3 = Permutation([[0, 1, 2, 3, 4], [5, 6, 7, 8, 9]])
assert _check_cycles_alt_sym(perm1) is True
assert _check_cycles_alt_sym(perm2) is False
assert _check_cycles_alt_sym(perm3) is False
def test_random_stab():
S = SymmetricGroup(5)
_random_el = Permutation([1, 3, 2, 0, 4])
_random_prec = {'rand': _random_el}
g = S.random_stab(2, _random_prec=_random_prec)
assert g == Permutation([1, 3, 2, 0, 4])
h = S.random_stab(1)
assert h(1) == 1
def test_orbit_rep():
G = DihedralGroup(6)
assert G.orbit_rep(1, 3) in [
Permutation([2, 3, 4, 5, 0, 1]),
Permutation([4, 3, 2, 1, 0, 5])
]
H = CyclicGroup(4) * G
assert H.orbit_rep(1, 5) is False
def test_riemann_invariants1():
baser, gensr = riemann_bsgs
g = Permutation([17, 44, 11, 3, 0, 19, 23, 15, 38, 4, 25, 27, 43, 36, 22, 14, 8, 30, 41, 20, 2, 10, 12, 28, 18, 1, 29, 13, 37, 42, 33, 7, 9, 31, 24, 26, 39, 5, 34, 47, 32, 6, 21, 40, 35, 46, 45, 16, 48, 49])
can = canonicalize(g, list(range(48)), 0, (baser, gensr, 12, 0))
assert can == [0, 2, 4, 6, 1, 3, 8, 10, 5, 7, 12, 14, 9, 11, 16, 18, 13, 15, 20, 22, 17, 19, 24, 26, 21, 23, 28, 30, 25, 27, 32, 34, 29, 31, 36, 38, 33, 35, 40, 42, 37, 39, 44, 46, 41, 43, 45, 47, 48, 49]
g = Permutation([0, 2, 4, 6, 7, 8, 10, 12, 14, 16, 18, 20, 19, 22, 24, 26, 5, 21, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 13, 48, 50, 52, 15, 49, 54, 56, 17, 33, 41, 58, 9, 23, 60, 62, 29, 35, 63, 64, 3, 45, 66, 68, 25, 37, 47, 57, 11, 31, 69, 70, 27, 39, 53, 72, 1, 59, 73, 74, 55, 61, 67, 76, 43, 65, 75, 78, 51, 71, 77, 79, 80, 81])
can = canonicalize(g, list(range(80)), 0, (baser, gensr, 20, 0))
assert can == [0, 2, 4, 6, 1, 8, 10, 12, 3, 14, 16, 18, 5, 20, 22, 24, 7, 26, 28, 30, 9, 15, 32, 34, 11, 36, 23, 38, 13, 40, 42, 44, 17, 39, 29, 46, 19, 48, 43, 50, 21, 45, 52, 54, 25, 56, 33, 58, 27, 60, 53, 62, 31, 51, 64, 66, 35, 65, 47, 68, 37, 70, 49, 72, 41, 74, 57, 76, 55, 67, 59, 78, 61, 69, 71, 75, 63, 79, 73, 77, 80, 81]
def test_transitivity_degree():
perm = Permutation([1, 2, 0])
C = PermutationGroup([perm])
assert C.transitivity_degree == 1
gen1 = Permutation([1, 2, 0, 3, 4])
gen2 = Permutation([1, 2, 3, 4, 0])
# alternating group of degree 5
Alt = PermutationGroup([gen1, gen2])
assert Alt.transitivity_degree == 3
def test_canonical_free():
# t = A^{d0 a1}*A_d0^a0
# ord = [a0,a1,d0,-d0]; g = [2,1,3,0,4,5]; dummies = [[2,3]]
# t_c = A_d0^a0*A^{d0 a1}
# can = [3,0, 2,1, 4,5]
g = Permutation([2, 1, 3, 0, 4, 5])
dummies = [[2, 3]]
can = canonicalize(g, dummies, [None], ([], [Permutation(3)], 2, 0))
assert can == [3, 0, 2, 1, 4, 5]
def test_is_solvable():
a = Permutation([1, 2, 0])
b = Permutation([1, 0, 2])
G = PermutationGroup([a, b])
assert G.is_solvable
a = Permutation([1, 2, 3, 4, 0])
b = Permutation([1, 0, 2, 3, 4])
G = PermutationGroup([a, b])
assert not G.is_solvable
def test_coset_factor():
a = Permutation([0, 2, 1])
G = PermutationGroup([a])
c = Permutation([2, 1, 0])
assert not G.coset_factor(c)
assert G.coset_rank(c) is None
a = Permutation([2, 0, 1, 3, 4, 5])
b = Permutation([2, 1, 3, 4, 5, 0])
g = PermutationGroup([a, b])
assert g.order() == 360
d = Permutation([1, 0, 2, 3, 4, 5])
assert not g.coset_factor(d.array_form)
assert not g.contains(d)
assert Permutation(2) in G
c = Permutation([1, 0, 2, 3, 5, 4])
v = g.coset_factor(c, True)
tr = g.basic_transversals
p = Permutation.rmul(*[tr[i][v[i]] for i in range(len(g.base))])
assert p == c
v = g.coset_factor(c)
p = Permutation.rmul(*v)
assert p == c
assert g.contains(c)
G = PermutationGroup([Permutation([2, 1, 0])])
p = Permutation([1, 0, 2])
assert G.coset_factor(p) == []
def test_make_perm():
assert cube.pgroup.make_perm(5, seed=list(range(5))) == \
Permutation([4, 7, 6, 5, 0, 3, 2, 1])
assert cube.pgroup.make_perm(7, seed=list(range(7))) == \
Permutation([6, 7, 3, 2, 5, 4, 0, 1])
random.seed(0)
assert cube.pgroup.make_perm(5) == Permutation([2, 1, 5, 6, 3, 0, 4, 7])
random.seed(0)
assert cube.pgroup.make_perm(5, seed=1) == Permutation([0, 3, 7, 4, 1, 2, 6, 5])
def test_equality():
p_1 = Permutation(0, 1, 3)
p_2 = Permutation(0, 2, 3)
p_3 = Permutation(0, 1, 2)
p_4 = Permutation(0, 1, 3)
g_1 = PermutationGroup(p_1, p_2)
g_2 = PermutationGroup(p_3, p_4)
g_3 = PermutationGroup(p_2, p_1)
assert g_1 == g_2
assert g_1.generators != g_2.generators
assert g_1 == g_3
def test_no_metric_symmetry():
# no metric symmetry
# A^d1_d0 * A^d0_d1; ord = [d0,-d0,d1,-d1]; g= [2,1,0,3,4,5]
# T_c = A^d0_d1 * A^d1_d0; can = [0,3,2,1,4,5]
g = Permutation([2, 1, 0, 3, 4, 5])
can = canonicalize(g, list(range(4)), None, [[], [Permutation(list(range(4)))], 2, 0])
assert can == [0, 3, 2, 1, 4, 5]
# A^d1_d2 * A^d0_d3 * A^d2_d1 * A^d3_d0
# ord = [d0,-d0,d1,-d1,d2,-d2,d3,-d3]
# 0 1 2 3 4 5 6 7
# g = [2,5,0,7,4,3,6,1,8,9]
# T_c = A^d0_d1 * A^d1_d0 * A^d2_d3 * A^d3_d2
# can = [0,3,2,1,4,7,6,5,8,9]
g = Permutation([2, 5, 0, 7, 4, 3, 6, 1, 8, 9])
# can = canonicalize(g, list(range(8)), 0, [[], [list(range(4))], 4, 0])
# assert can == [0, 2, 3, 1, 4, 6, 7, 5, 8, 9]
can = canonicalize(g, list(range(8)), None, [[], [Permutation(list(range(4)))], 4, 0])
assert can == [0, 3, 2, 1, 4, 7, 6, 5, 8, 9]
# A^d0_d2 * A^d1_d3 * A^d3_d0 * A^d2_d1
# g = [0,5,2,7,6,1,4,3,8,9]
# T_c = A^d0_d1 * A^d1_d2 * A^d2_d3 * A^d3_d0
# can = [0,3,2,5,4,7,6,1,8,9]
g = Permutation([0, 5, 2, 7, 6, 1, 4, 3, 8, 9])
can = canonicalize(g, list(range(8)), None, [[], [Permutation(list(range(4)))], 4, 0])
assert can == [0, 3, 2, 5, 4, 7, 6, 1, 8, 9]
g = Permutation([12, 7, 10, 3, 14, 13, 4, 11, 6, 1, 2, 9, 0, 15, 8, 5, 16, 17])
can = canonicalize(g, list(range(16)), None, [[], [Permutation(list(range(4)))], 8, 0])
assert can == [0, 3, 2, 5, 4, 7, 6, 1, 8, 11, 10, 13, 12, 15, 14, 9, 16, 17]
def test_make_perm():
assert cube.pgroup.make_perm(5, seed=list(range(5))) == \
Permutation([4, 7, 6, 5, 0, 3, 2, 1])
assert cube.pgroup.make_perm(7, seed=list(range(7))) == \
Permutation([6, 7, 3, 2, 5, 4, 0, 1])
pytest.raises(ValueError, lambda: cube.pgroup.make_perm({}, [0]))
random.seed(0)
assert cube.pgroup.make_perm(5) == Permutation([2, 1, 5, 6, 3, 0, 4, 7])
random.seed(0)
assert cube.pgroup.make_perm(5, seed=1) == Permutation(
[0, 3, 7, 4, 1, 2, 6, 5])
def test_derived_subgroup():
a = Permutation([1, 0, 2, 4, 3])
b = Permutation([0, 1, 3, 2, 4])
G = PermutationGroup([a, b])
C = G.derived_subgroup()
assert C.order() == 3
assert C.is_normal(G)
assert C.is_subgroup(G, 0)
assert not G.is_subgroup(C, 0)
gens_cube = [[1, 3, 5, 7, 0, 2, 4, 6], [1, 3, 0, 2, 5, 7, 4, 6]]
gens = [Permutation(p) for p in gens_cube]
G = PermutationGroup(gens)
C = G.derived_subgroup()
assert C.order() == 12
def test_is_normal():
gens_s5 = [Permutation(p) for p in [[1, 2, 3, 4, 0], [2, 1, 4, 0, 3]]]
G1 = PermutationGroup(gens_s5)
assert G1.order() == 120
gens_a5 = [Permutation(p) for p in [[1, 0, 3, 2, 4], [2, 1, 4, 3, 0]]]
G2 = PermutationGroup(gens_a5)
assert G2.order() == 60
assert G2.is_normal(G1)
gens3 = [Permutation(p) for p in [[2, 1, 3, 0, 4], [1, 2, 0, 3, 4]]]
G3 = PermutationGroup(gens3)
assert not G3.is_normal(G1)
assert G3.order() == 12
G4 = G1.normal_closure(G3.generators)
assert G4.order() == 60
gens5 = [Permutation(p) for p in [[1, 2, 3, 0, 4], [1, 2, 0, 3, 4]]]
G5 = PermutationGroup(gens5)
assert G5.order() == 24
G6 = G1.normal_closure(G5.generators)
assert G6.order() == 120
assert G1.is_subgroup(G6)
assert not G1.is_subgroup(G4)
assert G2.is_subgroup(G4)
s4 = PermutationGroup(Permutation(0, 1, 2, 3), Permutation(3)(0, 1))
s6 = PermutationGroup(Permutation(0, 1, 2, 3, 5), Permutation(5)(0, 1))
assert s6.is_normal(s4, strict=False)
assert not s4.is_normal(s6, strict=False)
def test_normal_closure():
# the normal closure of the trivial group is trivial
S = SymmetricGroup(3)
identity = Permutation([0, 1, 2])
closure = S.normal_closure(identity)
assert closure.is_trivial
# the normal closure of the entire group is the entire group
A = AlternatingGroup(4)
assert A.normal_closure(A).is_subgroup(A)
# brute-force verifications for subgroups
for i in (3, 4, 5):
S = SymmetricGroup(i)
A = AlternatingGroup(i)
D = DihedralGroup(i)
C = CyclicGroup(i)
for gp in (A, D, C):
assert _verify_normal_closure(S, gp)
# brute-force verifications for all elements of a group
for i in range(10):
S = SymmetricGroup(5)
elements = list(S.generate_dimino())
for element in elements:
assert _verify_normal_closure(S, element)
# small groups
small = []
for i in (1, 2, 3):
small.append(SymmetricGroup(i))
small.append(AlternatingGroup(i))
small.append(DihedralGroup(i))
small.append(CyclicGroup(i))
for gp in small:
for gp2 in small:
if gp2.is_subgroup(gp, 0) and gp2.degree == gp.degree:
assert _verify_normal_closure(gp, gp2)
def test_verify_centralizer():
# verified by GAP
S = SymmetricGroup(3)
A = AlternatingGroup(3)
triv = PermutationGroup([Permutation([0, 1, 2])])
assert _verify_centralizer(S, S, centr=triv)
assert _verify_centralizer(S, A, centr=A)
def test_strip():
D = DihedralGroup(5)
D.schreier_sims()
member = Permutation([4, 0, 1, 2, 3])
not_member1 = Permutation([0, 1, 4, 3, 2])
not_member2 = Permutation([3, 1, 4, 2, 0])
identity = Permutation([0, 1, 2, 3, 4])
res1 = _strip(member, D.base, D.basic_orbits, D.basic_transversals)
res2 = _strip(not_member1, D.base, D.basic_orbits, D.basic_transversals)
res3 = _strip(not_member2, D.base, D.basic_orbits, D.basic_transversals)
assert res1[0] == identity
assert res1[1] == len(D.base) + 1
assert res2[0] == not_member1
assert res2[1] == len(D.base) + 1
assert res3[0] != identity
assert res3[1] == 2
def test_handle_precomputed_bsgs():
A = AlternatingGroup(5)
A.schreier_sims()
base = A.base
strong_gens = A.strong_gens
result = _handle_precomputed_bsgs(base, strong_gens)
strong_gens_distr = _distribute_gens_by_base(base, strong_gens)
assert strong_gens_distr == result[2]
transversals = result[0]
orbits = result[1]
base_len = len(base)
for i in range(base_len):
for el in orbits[i]:
assert transversals[i][el](base[i]) == el
for j in range(i):
assert transversals[i][el](base[j]) == base[j]
order = 1
for i in range(base_len):
order *= len(orbits[i])
assert A.order() == order
_, transversals = _orbits_transversals_from_bsgs(base, strong_gens_distr)
assert transversals == _handle_precomputed_bsgs(base, strong_gens,
transversals)[0]
assert transversals == _handle_precomputed_bsgs(
base,
strong_gens,
transversals,
basic_orbits=transversals,
strong_gens_distr=strong_gens_distr)[0]
D = DihedralGroup(3)
D.schreier_sims()
assert (_handle_precomputed_bsgs(D.base,
D.strong_gens,
basic_orbits=D.basic_orbits) == ([{
0:
Permutation(2),
1:
Permutation(0, 1, 2),
2:
Permutation(0, 2)
}, {
1:
Permutation(2),
2:
Permutation(1, 2)
}], [[0, 1, 2], [1, 2]], [[
Permutation(0, 1, 2),
Permutation(0, 2),
Permutation(1, 2)
], [Permutation(1, 2)]]))
def test_strong_gens_from_distr():
strong_gens_distr = [[
Permutation([0, 2, 1]),
Permutation([1, 2, 0]),
Permutation([1, 0, 2])
], [Permutation([0, 2, 1])]]
assert _strong_gens_from_distr(strong_gens_distr) == \
[Permutation([0, 2, 1]),
Permutation([1, 2, 0]),
Permutation([1, 0, 2])]
assert _strong_gens_from_distr([[Permutation(0,
1)]]) == [Permutation(0, 1)]
def test_eq():
a = [[1, 2, 0, 3, 4, 5], [1, 0, 2, 3, 4, 5], [2, 1, 0, 3, 4, 5], [
1, 2, 0, 3, 4, 5]]
a = [Permutation(p) for p in a + [[1, 2, 3, 4, 5, 0]]]
g = Permutation([1, 2, 3, 4, 5, 0])
G1, G2, G3 = [PermutationGroup(x) for x in [a[:2], a[2:4], [g, g**2]]]
assert G1.order() == G2.order() == G3.order() == 6
assert G1.is_subgroup(G2)
assert not G1.is_subgroup(G3)
G4 = PermutationGroup([Permutation([0, 1])])
assert not G1.is_subgroup(G4)
assert G4.is_subgroup(G1, 0)
assert PermutationGroup(g, g).is_subgroup(PermutationGroup(g))
assert SymmetricGroup(3).is_subgroup(SymmetricGroup(4), 0)
assert SymmetricGroup(3).is_subgroup(SymmetricGroup(3)*CyclicGroup(5), 0)
assert not CyclicGroup(5).is_subgroup(SymmetricGroup(3)*CyclicGroup(5), 0)
assert CyclicGroup(3).is_subgroup(SymmetricGroup(3)*CyclicGroup(5), 0)
def test_has():
a = Permutation([1, 0])
G = PermutationGroup([a])
assert G.is_abelian
a = Permutation([2, 0, 1])
b = Permutation([2, 1, 0])
G = PermutationGroup([a, b])
assert not G.is_abelian
G = PermutationGroup([a])
assert G.has(a)
assert not G.has(b)
a = Permutation([2, 0, 1, 3, 4, 5])
b = Permutation([0, 2, 1, 3, 4])
assert PermutationGroup(a, b).degree == \
PermutationGroup(a, b).degree == 6
def test_centralizer():
# the centralizer of the trivial group is the entire group
S = SymmetricGroup(2)
assert S.centralizer(Permutation(list(range(2)))).is_subgroup(S)
A = AlternatingGroup(5)
assert A.centralizer(Permutation(list(range(5)))).is_subgroup(A)
# a centralizer in the trivial group is the trivial group itself
triv = PermutationGroup([Permutation([0, 1, 2, 3])])
D = DihedralGroup(4)
assert triv.centralizer(D).is_subgroup(triv)
# brute-force verifications for centralizers of groups
for i in (4, 5, 6):
S = SymmetricGroup(i)
A = AlternatingGroup(i)
C = CyclicGroup(i)
D = DihedralGroup(i)
for gp in (S, A, C, D):
for gp2 in (S, A, C, D):
if not gp2.is_subgroup(gp):
assert _verify_centralizer(gp, gp2)
# verify the centralizer for all elements of several groups
S = SymmetricGroup(5)
elements = list(S.generate_dimino())
for element in elements:
assert _verify_centralizer(S, element)
A = AlternatingGroup(5)
elements = list(A.generate_dimino())
for element in elements:
assert _verify_centralizer(A, element)
D = DihedralGroup(7)
elements = list(D.generate_dimino())
for element in elements:
assert _verify_centralizer(D, element)
# verify centralizers of small groups within small groups
small = []
for i in (1, 2, 3):
small.append(SymmetricGroup(i))
small.append(AlternatingGroup(i))
small.append(DihedralGroup(i))
small.append(CyclicGroup(i))
for gp in small:
for gp2 in small:
if gp.degree == gp2.degree:
assert _verify_centralizer(gp, gp2)
def test_tensorsymmetry():
sym = tensorsymmetry([1]*2)
sym1 = TensorSymmetry(get_symmetric_group_sgs(2))
assert sym == sym1
sym = tensorsymmetry([2])
sym1 = TensorSymmetry(get_symmetric_group_sgs(2, 1))
assert sym == sym1
sym2 = tensorsymmetry()
assert sym2.base == Tuple() and sym2.generators == Tuple(Permutation(1))
pytest.raises(NotImplementedError, lambda: tensorsymmetry([2, 1]))
def test_pointwise_stabilizer():
S = SymmetricGroup(2)
stab = S.pointwise_stabilizer([0])
assert stab.generators == [Permutation(1)]
S = SymmetricGroup(5)
points = []
stab = S
for point in (2, 0, 3, 4, 1):
stab = stab.stabilizer(point)
points.append(point)
assert S.pointwise_stabilizer(points).is_subgroup(stab)
def test_distribute_gens_by_base():
base = [0, 1, 2]
gens = [
Permutation([0, 1, 2, 3]),
Permutation([0, 1, 3, 2]),
Permutation([0, 2, 3, 1]),
Permutation([3, 2, 1, 0])
]
assert _distribute_gens_by_base(base, gens) == [
gens,
[
Permutation([0, 1, 2, 3]),
Permutation([0, 1, 3, 2]),
Permutation([0, 2, 3, 1])
], [Permutation([0, 1, 2, 3]),
Permutation([0, 1, 3, 2])]
]
def test_generate():
a = Permutation([1, 0])
g = list(PermutationGroup([a]).generate())
assert g == [Permutation([0, 1]), Permutation([1, 0])]
assert len(list(PermutationGroup(Permutation((0, 1))).generate())) == 1
g = PermutationGroup([a]).generate(method='dimino')
assert list(g) == [Permutation([0, 1]), Permutation([1, 0])]
a = Permutation([2, 0, 1])
b = Permutation([2, 1, 0])
G = PermutationGroup([a, b])
g = G.generate()
v1 = [p.array_form for p in list(g)]
v1.sort()
assert v1 == [[0, 1, 2], [0, 2, 1], [1, 0, 2], [1, 2, 0], [2, 0,
1], [2, 1, 0]]
v2 = list(G.generate(method='dimino', af=True))
assert v1 == sorted(v2)
a = Permutation([2, 0, 1, 3, 4, 5])
b = Permutation([2, 1, 3, 4, 5, 0])
g = PermutationGroup([a, b]).generate(af=True)
assert len(list(g)) == 360