def test_mul():
from sympy.abc import x
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
a, b, c, d = tensor_indices('a,b,c,d', Lorentz)
sym = tensorsymmetry([1]*2)
t = TensMul.from_data(S.One, [], [], [])
assert str(t) == '1'
A, B = tensorhead('A B', [Lorentz]*2, [[1]*2])
t = (1 + x)*A(a, b)
assert str(t) == '(x + 1)*A(a, b)'
assert t.types == [Lorentz]
assert t.rank == 2
assert t.dum == []
assert t.coeff == 1 + x
assert sorted(t.free) == [(a, 0, 0), (b, 1, 0)]
assert t.components == [A]
t = A(-b, a)*B(-a, c)*A(-c, d)
t1 = tensor_mul(*t.split())
assert t == t(-b, d)
assert t == t1
assert tensor_mul(*[]) == TensMul.from_data(S.One, [], [], [])
t = TensMul.from_data(1, [], [], [])
zsym = tensorsymmetry()
typ = TensorType([], zsym)
C = typ('C')
assert str(C()) == 'C'
assert str(t) == '1'
assert t.split()[0] == t
raises(ValueError, lambda: TIDS.free_dum_from_indices(a, a))
raises(ValueError, lambda: TIDS.free_dum_from_indices(-a, -a))
raises(ValueError, lambda: A(a, b)*A(a, c))
t = A(a, b)*A(-a, c)
raises(ValueError, lambda: t(a, b, c))
def test_mul():
from sympy.abc import x
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
a, b, c, d = tensor_indices('a,b,c,d', Lorentz)
sym = tensorsymmetry([1] * 2)
t = TensMul.from_data(S.One, [], [], [])
assert str(t) == '1'
A, B = tensorhead('A B', [Lorentz] * 2, [[1] * 2])
t = (1 + x) * A(a, b)
assert str(t) == '(x + 1)*A(a, b)'
assert t.types == [Lorentz]
assert t.rank == 2
assert t.dum == []
assert t.coeff == 1 + x
assert sorted(t.free) == [(a, 0, 0), (b, 1, 0)]
assert t.components == [A]
t = A(-b, a) * B(-a, c) * A(-c, d)
t1 = tensor_mul(*t.split())
assert t == t(-b, d)
assert t == t1
assert tensor_mul(*[]) == TensMul.from_data(S.One, [], [], [])
t = TensMul.from_data(1, [], [], [])
zsym = tensorsymmetry()
typ = TensorType([], zsym)
C = typ('C')
assert str(C()) == 'C'
assert str(t) == '1'
assert t.split()[0] == t
raises(ValueError, lambda: TIDS.free_dum_from_indices(a, a))
raises(ValueError, lambda: TIDS.free_dum_from_indices(-a, -a))
raises(ValueError, lambda: A(a, b) * A(a, c))
t = A(a, b) * A(-a, c)
raises(ValueError, lambda: t(a, b, c))
def test_tensorsymmetry():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
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))
raises(NotImplementedError, lambda: tensorsymmetry([2, 1]))
def test_tensorsymmetry():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
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))
raises(NotImplementedError, lambda: tensorsymmetry([2, 1]))
def test_canonicalize_no_dummies():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
a, b, c, d = tensor_indices('a, b, c, d', Lorentz)
sym1 = tensorsymmetry([1])
sym2 = tensorsymmetry([1] * 2)
sym2a = tensorsymmetry([2])
# A commuting
# A^c A^b A^a
# T_c = A^a A^b A^c
S1 = TensorType([Lorentz], sym1)
A = S1('A')
t = A(c) * A(b) * A(a)
tc = t.canon_bp()
assert str(tc) == 'A(a)*A(b)*A(c)'
# A anticommuting
# A^c A^b A^a
# T_c = -A^a A^b A^c
A = S1('A', 1)
t = A(c) * A(b) * A(a)
tc = t.canon_bp()
assert str(tc) == '-A(a)*A(b)*A(c)'
# A commuting and symmetric
# A^{b,d}*A^{c,a}
# T_c = A^{a c}*A^{b d}
S2 = TensorType([Lorentz] * 2, sym2)
A = S2('A')
t = A(b, d) * A(c, a)
tc = t.canon_bp()
assert str(tc) == 'A(a, c)*A(b, d)'
# A anticommuting and symmetric
# A^{b,d}*A^{c,a}
# T_c = -A^{a c}*A^{b d}
A = S2('A', 1)
t = A(b, d) * A(c, a)
tc = t.canon_bp()
assert str(tc) == '-A(a, c)*A(b, d)'
# A^{c,a}*A^{b,d}
# T_c = A^{a c}*A^{b d}
t = A(c, a) * A(b, d)
tc = t.canon_bp()
assert str(tc) == 'A(a, c)*A(b, d)'
def test_TensorIndexType():
D = Symbol('D')
G = Metric('g', False)
Lorentz = TensorIndexType('Lorentz', metric=G, dim=D, dummy_fmt='L')
m0, m1, m2, m3, m4 = tensor_indices('m0:5', Lorentz)
sym2 = tensorsymmetry([1]*2)
sym2n = tensorsymmetry(*get_symmetric_group_sgs(2))
assert sym2 == sym2n
g = Lorentz.metric
assert str(g) == 'g(Lorentz,Lorentz)'
assert Lorentz.eps_dim == Lorentz.dim
TSpace = TensorIndexType('TSpace')
i0, i1 = tensor_indices('i0 i1', TSpace)
g = TSpace.metric
A = tensorhead('A', [TSpace]*2, [[1]*2])
assert str(A(i0,-i0).canon_bp()) == 'A(TSpace_0, -TSpace_0)'
def test_canonicalize_no_dummies():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
a, b, c, d = tensor_indices('a, b, c, d', Lorentz)
sym1 = tensorsymmetry([1])
sym2 = tensorsymmetry([1]*2)
sym2a = tensorsymmetry([2])
# A commuting
# A^c A^b A^a
# T_c = A^a A^b A^c
S1 = TensorType([Lorentz], sym1)
A = S1('A')
t = A(c)*A(b)*A(a)
tc = t.canon_bp()
assert str(tc) == 'A(a)*A(b)*A(c)'
# A anticommuting
# A^c A^b A^a
# T_c = -A^a A^b A^c
A = S1('A', 1)
t = A(c)*A(b)*A(a)
tc = t.canon_bp()
assert str(tc) == '-A(a)*A(b)*A(c)'
# A commuting and symmetric
# A^{b,d}*A^{c,a}
# T_c = A^{a c}*A^{b d}
S2 = TensorType([Lorentz]*2, sym2)
A = S2('A')
t = A(b, d)*A(c, a)
tc = t.canon_bp()
assert str(tc) == 'A(a, c)*A(b, d)'
# A anticommuting and symmetric
# A^{b,d}*A^{c,a}
# T_c = -A^{a c}*A^{b d}
A = S2('A', 1)
t = A(b, d)*A(c, a)
tc = t.canon_bp()
assert str(tc) == '-A(a, c)*A(b, d)'
# A^{c,a}*A^{b,d}
# T_c = A^{a c}*A^{b d}
t = A(c, a)*A(b, d)
tc = t.canon_bp()
assert str(tc) == 'A(a, c)*A(b, d)'
def test_TensorIndexType():
D = Symbol("D")
G = Metric("g", False)
Lorentz = TensorIndexType("Lorentz", metric=G, dim=D, dummy_fmt="L")
m0, m1, m2, m3, m4 = tensor_indices("m0:5", Lorentz)
sym2 = tensorsymmetry([1] * 2)
sym2n = tensorsymmetry(*get_symmetric_group_sgs(2))
assert sym2 == sym2n
g = Lorentz.metric
assert str(g) == "g(Lorentz,Lorentz)"
assert Lorentz.eps_dim == Lorentz.dim
TSpace = TensorIndexType("TSpace")
i0, i1 = tensor_indices("i0 i1", TSpace)
g = TSpace.metric
A = tensorhead("A", [TSpace] * 2, [[1] * 2])
assert str(A(i0, -i0).canon_bp()) == "A(TSpace_0, -TSpace_0)"
def test_TensorIndexType():
D = Symbol('D')
G = Metric('g', False)
Lorentz = TensorIndexType('Lorentz', metric=G, dim=D, dummy_fmt='L')
m0, m1, m2, m3, m4 = tensor_indices('m0:5', Lorentz)
sym2 = tensorsymmetry([1] * 2)
sym2n = tensorsymmetry(*get_symmetric_group_sgs(2))
assert sym2 == sym2n
g = Lorentz.metric
assert str(g) == 'g(Lorentz,Lorentz)'
assert Lorentz.eps_dim == Lorentz.dim
TSpace = TensorIndexType('TSpace')
i0, i1 = tensor_indices('i0 i1', TSpace)
g = TSpace.metric
A = tensorhead('A', [TSpace] * 2, [[1] * 2])
assert str(A(i0, -i0).canon_bp()) == 'A(TSpace_0, -TSpace_0)'
def test_TensorType():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
sym = tensorsymmetry([1] * 2)
A = tensorhead('A', [Lorentz] * 2, [[1] * 2])
assert A.typ == TensorType([Lorentz] * 2, sym)
assert A.types == [Lorentz]
typ = TensorType([Lorentz] * 2, sym)
assert str(typ) == "TensorType(['Lorentz', 'Lorentz'])"
raises(ValueError, lambda: typ(2))
def test_TensorType():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
sym = tensorsymmetry([1]*2)
A = tensorhead('A', [Lorentz]*2, [[1]*2])
assert A.typ == TensorType([Lorentz]*2, sym)
assert A.types == [Lorentz]
typ = TensorType([Lorentz]*2, sym)
assert str(typ) == "TensorType(['Lorentz', 'Lorentz'])"
raises(ValueError, lambda: typ(2))
def test_TensorHead():
assert TensAdd() == 0
# simple example of algebraic expression
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
a,b = tensor_indices('a,b', Lorentz)
# A, B symmetric
A = tensorhead('A', [Lorentz]*2, [[1]*2])
assert A.rank == 2
assert A.symmetry == tensorsymmetry([1]*2)
def test_TensorHead():
assert TensAdd() == 0
# simple example of algebraic expression
Lorentz = TensorIndexType("Lorentz", dummy_fmt="L")
a, b = tensor_indices("a,b", Lorentz)
# A, B symmetric
A = tensorhead("A", [Lorentz] * 2, [[1] * 2])
assert A.rank == 2
assert A.symmetry == tensorsymmetry([1] * 2)
def test_TensorHead():
assert TensAdd() == 0
# simple example of algebraic expression
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
a, b = tensor_indices('a,b', Lorentz)
# A, B symmetric
A = tensorhead('A', [Lorentz] * 2, [[1] * 2])
assert A.rank == 2
assert A.symmetry == tensorsymmetry([1] * 2)
def test_Tensor():
from sympy.tensor.tensor import tensorsymmetry
(coords, metric) = _generate_simple()
T = Tensor("T", coords, metric)
assert isinstance(T, TensorHead)
assert T.as_array() == Array(coords)
assert T.covar == (1,)
assert T.symmetry == tensorsymmetry([1])
def test_riemann_cyclic_replace():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
m0, m1, m2, m3 = tensor_indices('m:4', Lorentz)
symr = tensorsymmetry([2, 2])
R = tensorhead('R', [Lorentz]*4, [[2, 2]])
t = R(m0, m2, m1, m3)
t1 = riemann_cyclic_replace(t)
t1a = -S.One/3*R(m0, m3, m2, m1) + S.One/3*R(m0, m1, m2, m3) + Rational(2, 3)*R(m0, m2, m1, m3)
assert t1 == t1a
def test_hash():
D = Symbol('D')
Lorentz = TensorIndexType('Lorentz', dim=D, dummy_fmt='L')
a,b,c,d,e = tensor_indices('a,b,c,d,e', Lorentz)
g = Lorentz.metric
p, q = tensorhead('p q', [Lorentz], [[1]])
p_type = p.args[1]
t1 = p(a)*q(b)
t2 = p(a)*p(b)
assert hash(t1) != hash(t2)
t3 = p(a)*p(b) + g(a,b)
t4 = p(a)*p(b) - g(a,b)
assert hash(t3) != hash(t4)
assert a.func(*a.args) == a
assert Lorentz.func(*Lorentz.args) == Lorentz
assert g.func(*g.args) == g
assert p.func(*p.args) == p
assert p_type.func(*p_type.args) == p_type
assert p(a).func(*(p(a)).args) == p(a)
assert t1.func(*t1.args) == t1
assert t2.func(*t2.args) == t2
assert t3.func(*t3.args) == t3
assert t4.func(*t4.args) == t4
assert hash(a.func(*a.args)) == hash(a)
assert hash(Lorentz.func(*Lorentz.args)) == hash(Lorentz)
assert hash(g.func(*g.args)) == hash(g)
assert hash(p.func(*p.args)) == hash(p)
assert hash(p_type.func(*p_type.args)) == hash(p_type)
assert hash(p(a).func(*(p(a)).args)) == hash(p(a))
assert hash(t1.func(*t1.args)) == hash(t1)
assert hash(t2.func(*t2.args)) == hash(t2)
assert hash(t3.func(*t3.args)) == hash(t3)
assert hash(t4.func(*t4.args)) == hash(t4)
def check_all(obj):
return all([isinstance(_, Basic) for _ in obj.args])
assert check_all(a)
assert check_all(Lorentz)
assert check_all(g)
assert check_all(p)
assert check_all(p_type)
assert check_all(p(a))
assert check_all(t1)
assert check_all(t2)
assert check_all(t3)
assert check_all(t4)
tsymmetry = tensorsymmetry([2], [1], [1, 1, 1])
assert tsymmetry.func(*tsymmetry.args) == tsymmetry
assert hash(tsymmetry.func(*tsymmetry.args)) == hash(tsymmetry)
assert check_all(tsymmetry)
def test_hash():
D = Symbol('D')
Lorentz = TensorIndexType('Lorentz', dim=D, dummy_fmt='L')
a, b, c, d, e = tensor_indices('a,b,c,d,e', Lorentz)
g = Lorentz.metric
p, q = tensorhead('p q', [Lorentz], [[1]])
p_type = p.args[1]
t1 = p(a) * q(b)
t2 = p(a) * p(b)
assert hash(t1) != hash(t2)
t3 = p(a) * p(b) + g(a, b)
t4 = p(a) * p(b) - g(a, b)
assert hash(t3) != hash(t4)
assert a.func(*a.args) == a
assert Lorentz.func(*Lorentz.args) == Lorentz
assert g.func(*g.args) == g
assert p.func(*p.args) == p
assert p_type.func(*p_type.args) == p_type
assert p(a).func(*(p(a)).args) == p(a)
assert t1.func(*t1.args) == t1
assert t2.func(*t2.args) == t2
assert t3.func(*t3.args) == t3
assert t4.func(*t4.args) == t4
assert hash(a.func(*a.args)) == hash(a)
assert hash(Lorentz.func(*Lorentz.args)) == hash(Lorentz)
assert hash(g.func(*g.args)) == hash(g)
assert hash(p.func(*p.args)) == hash(p)
assert hash(p_type.func(*p_type.args)) == hash(p_type)
assert hash(p(a).func(*(p(a)).args)) == hash(p(a))
assert hash(t1.func(*t1.args)) == hash(t1)
assert hash(t2.func(*t2.args)) == hash(t2)
assert hash(t3.func(*t3.args)) == hash(t3)
assert hash(t4.func(*t4.args)) == hash(t4)
def check_all(obj):
return all([isinstance(_, Basic) for _ in obj.args])
assert check_all(a)
assert check_all(Lorentz)
assert check_all(g)
assert check_all(p)
assert check_all(p_type)
assert check_all(p(a))
assert check_all(t1)
assert check_all(t2)
assert check_all(t3)
assert check_all(t4)
tsymmetry = tensorsymmetry([2], [1], [1, 1, 1])
assert tsymmetry.func(*tsymmetry.args) == tsymmetry
assert hash(tsymmetry.func(*tsymmetry.args)) == hash(tsymmetry)
assert check_all(tsymmetry)
def test_riemann_cyclic_replace():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
m0, m1, m2, m3 = tensor_indices('m:4', Lorentz)
symr = tensorsymmetry([2, 2])
R = tensorhead('R', [Lorentz] * 4, [[2, 2]])
t = R(m0, m2, m1, m3)
t1 = riemann_cyclic_replace(t)
t1a = -S.One / 3 * R(m0, m3, m2, m1) + S.One / 3 * R(
m0, m1, m2, m3) + Rational(2, 3) * R(m0, m2, m1, m3)
assert t1 == t1a
def __new__(cls, dim=4, eps_dim=4):
key = (dim, eps_dim)
if key in GammaMatrixHead._gmhd:
return GammaMatrixHead._gmhd[key]
lorentz = _LorentzContainer(*key)
gmh = TensorHead.__new__(cls, "gamma", TensorType(Tuple(lorentz), tensorsymmetry([1])), comm=2)
GammaMatrixHead._gmhd[key] = gmh
gmh.Lorentz = lorentz
return gmh
def __new__(cls, dim=4, eps_dim=4):
key = (dim, eps_dim)
if key in GammaMatrixHead._gmhd:
return GammaMatrixHead._gmhd[key]
lorentz = _LorentzContainer(*key)
gmh = TensorHead.__new__(cls,
"gamma",
TensorType(
Tuple(lorentz, DiracSpinorIndex,
DiracSpinorIndex),
tensorsymmetry([1], [1], [1])),
comm=2,
matrix_behavior=True)
GammaMatrixHead._gmhd[key] = gmh
gmh.LorentzIndex = lorentz
return gmh
def __new__(cls, symbol, matrix, metric, **kwargs):
"""
Create a new Tensor object.
Parameters
----------
symbol : str
Name of the tensor and the symbol to denote it by when printed.
matrix : (list, tuple, ~sympy.Matrix, ~sympy.Array)
Matrix representation of the tensor to be used in substitution.
Can be of any type that is acceptable by ~sympy.Array.
metric : Metric
Classify the tensor as being defined in terms of a metric.
Notes
-----
If the parameter ``symmetry`` is passed, the tensor object will defined
using a specific symmetry. Example values are (see sympy documentation
for the function ``tensorsymmetry``):
``[[1]]`` vector
``[[1]*n]`` symmetric tensor of rank ``n``
``[[n]]`` antisymmetric tensor of rank ``n``
``[[2, 2]]`` monoterm slot symmetry of the Riemann tensor
``[[1],[1]]`` vector*vector
``[[2],[1],[1]]`` (antisymmetric tensor)*vector*vector
Additionally, the parameter ``covar`` indicates that the passed array
corresponds to the covariance of the tensor it is intended to describe.
Lastly, the parameter ``comm`` is used to indicate what commutation
group the tensor belongs to. In other words, it describes what other
types of tensors the one being created is allowed to commute with.
There are three commutation groups: ``general`` for ordinary tensors,
``metric`` for metric tensors, and ``partial`` for partial derivatives.
Examples
--------
>>> from sympy import diag, symbols
>>> from einsteinpy.symbolic.tensor import Tensor, indices, expand_tensor
>>> from einsteinpy.symbolic.metric import Metric
>>> E1, E2, E3, B1, B2, B3 = symbols('E1:4 B1:4')
>>> em = [[0, -E1, -E2, -E3],
[E1, 0, -B3, B2],
[E2, B3, 0, -B1],
[E3, -B2, B1, 0]]
>>> t, x, y, z = symbols('t x y z')
>>> eta = Metric('eta', [t, x, y, z], diag(1, -1, -1, -1))
>>> F = Tensor('F', em, eta, symmetry=[[2]])
>>> mu, nu = indices('mu nu', eta)
>>> expr = F(mu, nu) + F(nu, mu)
>>> expand_tensor(expr)
0
>>> expr = F(mu, nu) * F(-mu, -nu)
>>> expand_tensor(expr)
2*B_1**2 + 2*B_2**2 + 2*B_3**2 - 2*E_1**2 - 2*E_2**2 - 2*E_3**2
"""
array = Array(matrix)
sym = kwargs.pop("symmetry", [[1] * array.rank()])
sym = tensorsymmetry(*sym)
symtype = TensorType(array.rank() * [metric], sym)
comm = kwargs.pop("comm", "general")
covar = tuple(kwargs.pop("covar", array.rank() * [1]))
if len(covar) != array.rank():
raise ValueError(
"covariance signature {} does not match tensor rank {}".format(
covar, array.rank()))
count = defaultdict(int) # type: dict
def dummy_fmt_gen(idxtype):
# generate a generic index for the entry in ReplacementManager.
fmt = idxtype.dummy_fmt
n = count[idxtype]
count[idxtype] += 1
return fmt % n
obj = TensorHead.__new__(cls, symbol, symtype, comm=comm, **kwargs)
obj = AbstractTensor.__new__(cls, obj, array)
# resolves a bug with pretty printing.
obj.__class__.__name__ = "TensorHead"
obj.covar = covar
idx_names = map(dummy_fmt_gen, obj.index_types)
idx_generator = map(Index, idx_names, obj.index_types)
idxs = [
idx if covar[pos] > 0 else -idx
for pos, idx in enumerate(idx_generator)
]
ReplacementManager[obj(*idxs)] = array
return obj
def test_canonicalize_no_slot_sym():
# A_d0 * B^d0; T_c = A^d0*B_d0
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
a, b, d0, d1 = tensor_indices('a,b,d0,d1', Lorentz)
sym1 = tensorsymmetry([1])
S1 = TensorType([Lorentz], sym1)
A, B = S1('A,B')
t = A(-d0) * B(d0)
tc = t.canon_bp()
assert str(tc) == 'A(L_0)*B(-L_0)'
# A^a * B^b; T_c = T
t = A(a) * B(b)
tc = t.canon_bp()
assert tc == t
# B^b * A^a
t1 = B(b) * A(a)
tc = t1.canon_bp()
assert str(tc) == 'A(a)*B(b)'
# A symmetric
# A^{b}_{d0}*A^{d0, a}; T_c = A^{a d0}*A{b}_{d0}
sym2 = tensorsymmetry([1] * 2)
S2 = TensorType([Lorentz] * 2, sym2)
A = S2('A')
t = A(b, -d0) * A(d0, a)
tc = t.canon_bp()
assert str(tc) == 'A(a, L_0)*A(b, -L_0)'
# A^{d1}_{d0}*B^d0*C_d1
# T_c = A^{d0 d1}*B_d0*C_d1
B, C = S1('B,C')
t = A(d1, -d0) * B(d0) * C(-d1)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1)*B(-L_0)*C(-L_1)'
# A without symmetry
# A^{d1}_{d0}*B^d0*C_d1 ord=[d0,-d0,d1,-d1]; g = [2,1,0,3,4,5]
# T_c = A^{d0 d1}*B_d1*C_d0; can = [0,2,3,1,4,5]
nsym2 = tensorsymmetry([1], [1])
NS2 = TensorType([Lorentz] * 2, nsym2)
A = NS2('A')
B, C = S1('B, C')
t = A(d1, -d0) * B(d0) * C(-d1)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1)*B(-L_1)*C(-L_0)'
# A, B without symmetry
# A^{d1}_{d0}*B_{d1}^{d0}
# T_c = A^{d0 d1}*B_{d0 d1}
B = NS2('B')
t = A(d1, -d0) * B(-d1, d0)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1)*B(-L_0, -L_1)'
# A_{d0}^{d1}*B_{d1}^{d0}
# T_c = A^{d0 d1}*B_{d1 d0}
t = A(-d0, d1) * B(-d1, d0)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1)*B(-L_1, -L_0)'
# A, B, C without symmetry
# A^{d1 d0}*B_{a d0}*C_{d1 b}
# T_c=A^{d0 d1}*B_{a d1}*C_{d0 b}
C = NS2('C')
t = A(d1, d0) * B(-a, -d0) * C(-d1, -b)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1)*B(-a, -L_1)*C(-L_0, -b)'
# A symmetric, B and C without symmetry
# A^{d1 d0}*B_{a d0}*C_{d1 b}
# T_c = A^{d0 d1}*B_{a d0}*C_{d1 b}
A = S2('A')
t = A(d1, d0) * B(-a, -d0) * C(-d1, -b)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1)*B(-a, -L_0)*C(-L_1, -b)'
# A and C symmetric, B without symmetry
# A^{d1 d0}*B_{a d0}*C_{d1 b} ord=[a,b,d0,-d0,d1,-d1]
# T_c = A^{d0 d1}*B_{a d0}*C_{b d1}
C = S2('C')
t = A(d1, d0) * B(-a, -d0) * C(-d1, -b)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1)*B(-a, -L_0)*C(-b, -L_1)'
def test_canonicalize1():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
a, a0, a1, a2, a3, b, d0, d1, d2, d3 = \
tensor_indices('a,a0,a1,a2,a3,b,d0,d1,d2,d3', Lorentz)
sym1 = tensorsymmetry([1])
base3, gens3 = get_symmetric_group_sgs(3)
sym2 = tensorsymmetry([1] * 2)
sym2a = tensorsymmetry([2])
sym3 = tensorsymmetry([1] * 3)
sym3a = tensorsymmetry([3])
# A_d0*A^d0; ord = [d0,-d0]
# T_c = A^d0*A_d0
S1 = TensorType([Lorentz], sym1)
A = S1('A')
t = A(-d0) * A(d0)
tc = t.canon_bp()
assert str(tc) == 'A(L_0)*A(-L_0)'
# A commuting
# A_d0*A_d1*A_d2*A^d2*A^d1*A^d0
# T_c = A^d0*A_d0*A^d1*A_d1*A^d2*A_d2
t = A(-d0) * A(-d1) * A(-d2) * A(d2) * A(d1) * A(d0)
tc = t.canon_bp()
assert str(tc) == 'A(L_0)*A(-L_0)*A(L_1)*A(-L_1)*A(L_2)*A(-L_2)'
# A anticommuting
# A_d0*A_d1*A_d2*A^d2*A^d1*A^d0
# T_c 0
A = S1('A', 1)
t = A(-d0) * A(-d1) * A(-d2) * A(d2) * A(d1) * A(d0)
tc = t.canon_bp()
assert tc == 0
# A commuting symmetric
# A^{d0 b}*A^a_d1*A^d1_d0
# T_c = A^{a d0}*A^{b d1}*A_{d0 d1}
S2 = TensorType([Lorentz] * 2, sym2)
A = S2('A')
t = A(d0, b) * A(a, -d1) * A(d1, -d0)
tc = t.canon_bp()
assert str(tc) == 'A(a, L_0)*A(b, L_1)*A(-L_0, -L_1)'
# A, B commuting symmetric
# A^{d0 b}*A^d1_d0*B^a_d1
# T_c = A^{b d0}*A_d0^d1*B^a_d1
B = S2('B')
t = A(d0, b) * A(d1, -d0) * B(a, -d1)
tc = t.canon_bp()
assert str(tc) == 'A(b, L_0)*A(-L_0, L_1)*B(a, -L_1)'
# A commuting symmetric
# A^{d1 d0 b}*A^{a}_{d1 d0}; ord=[a,b, d0,-d0,d1,-d1]
# T_c = A^{a d0 d1}*A^{b}_{d0 d1}
S3 = TensorType([Lorentz] * 3, sym3)
A = S3('A')
t = A(d1, d0, b) * A(a, -d1, -d0)
tc = t.canon_bp()
assert str(tc) == 'A(a, L_0, L_1)*A(b, -L_0, -L_1)'
# A^{d3 d0 d2}*A^a0_{d1 d2}*A^d1_d3^a1*A^{a2 a3}_d0
# T_c = A^{a0 d0 d1}*A^a1_d0^d2*A^{a2 a3 d3}*A_{d1 d2 d3}
t = A(d3, d0, d2) * A(a0, -d1, -d2) * A(d1, -d3, a1) * A(a2, a3, -d0)
tc = t.canon_bp()
assert str(
tc
) == 'A(a0, L_0, L_1)*A(a1, -L_0, L_2)*A(a2, a3, L_3)*A(-L_1, -L_2, -L_3)'
# A commuting symmetric, B antisymmetric
# A^{d0 d1 d2} * A_{d2 d3 d1} * B_d0^d3
# in this esxample and in the next three,
# renaming dummy indices and using symmetry of A,
# T = A^{d0 d1 d2} * A_{d0 d1 d3} * B_d2^d3
# can = 0
S2a = TensorType([Lorentz] * 2, sym2a)
A = S3('A')
B = S2a('B')
t = A(d0, d1, d2) * A(-d2, -d3, -d1) * B(-d0, d3)
tc = t.canon_bp()
assert tc == 0
# A anticommuting symmetric, B anticommuting
# A^{d0 d1 d2} * A_{d2 d3 d1} * B_d0^d3
# T_c = A^{d0 d1 d2} * A_{d0 d1}^d3 * B_{d2 d3}
A = S3('A', 1)
B = S2a('B')
t = A(d0, d1, d2) * A(-d2, -d3, -d1) * B(-d0, d3)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1, L_2)*A(-L_0, -L_1, L_3)*B(-L_2, -L_3)'
# A anticommuting symmetric, B antisymmetric commuting, antisymmetric metric
# A^{d0 d1 d2} * A_{d2 d3 d1} * B_d0^d3
# T_c = -A^{d0 d1 d2} * A_{d0 d1}^d3 * B_{d2 d3}
Spinor = TensorIndexType('Spinor', metric=1, dummy_fmt='S')
a, a0, a1, a2, a3, b, d0, d1, d2, d3 = \
tensor_indices('a,a0,a1,a2,a3,b,d0,d1,d2,d3', Spinor)
S3 = TensorType([Spinor] * 3, sym3)
S2a = TensorType([Spinor] * 2, sym2a)
A = S3('A', 1)
B = S2a('B')
t = A(d0, d1, d2) * A(-d2, -d3, -d1) * B(-d0, d3)
tc = t.canon_bp()
assert str(tc) == '-A(S_0, S_1, S_2)*A(-S_0, -S_1, S_3)*B(-S_2, -S_3)'
# A anticommuting symmetric, B antisymmetric anticommuting,
# no metric symmetry
# A^{d0 d1 d2} * A_{d2 d3 d1} * B_d0^d3
# T_c = A^{d0 d1 d2} * A_{d0 d1 d3} * B_d2^d3
Mat = TensorIndexType('Mat', metric=None, dummy_fmt='M')
a, a0, a1, a2, a3, b, d0, d1, d2, d3 = \
tensor_indices('a,a0,a1,a2,a3,b,d0,d1,d2,d3', Mat)
S3 = TensorType([Mat] * 3, sym3)
S2a = TensorType([Mat] * 2, sym2a)
A = S3('A', 1)
B = S2a('B')
t = A(d0, d1, d2) * A(-d2, -d3, -d1) * B(-d0, d3)
tc = t.canon_bp()
assert str(tc) == 'A(M_0, M_1, M_2)*A(-M_0, -M_1, -M_3)*B(-M_2, M_3)'
# Gamma anticommuting
# Gamma_{mu nu} * gamma^rho * Gamma^{nu mu alpha}
# T_c = -Gamma^{mu nu} * gamma^rho * Gamma_{alpha mu nu}
S1 = TensorType([Lorentz], sym1)
S2a = TensorType([Lorentz] * 2, sym2a)
S3a = TensorType([Lorentz] * 3, sym3a)
alpha, beta, gamma, mu, nu, rho = \
tensor_indices('alpha,beta,gamma,mu,nu,rho', Lorentz)
Gamma = S1('Gamma', 2)
Gamma2 = S2a('Gamma', 2)
Gamma3 = S3a('Gamma', 2)
t = Gamma2(-mu, -nu) * Gamma(rho) * Gamma3(nu, mu, alpha)
tc = t.canon_bp()
assert str(tc) == '-Gamma(L_0, L_1)*Gamma(rho)*Gamma(alpha, -L_0, -L_1)'
# Gamma_{mu nu} * Gamma^{gamma beta} * gamma_rho * Gamma^{nu mu alpha}
# T_c = Gamma^{mu nu} * Gamma^{beta gamma} * gamma_rho * Gamma^alpha_{mu nu}
t = Gamma2(mu, nu) * Gamma2(beta, gamma) * Gamma(-rho) * Gamma3(
alpha, -mu, -nu)
tc = t.canon_bp()
assert str(
tc
) == 'Gamma(L_0, L_1)*Gamma(beta, gamma)*Gamma(-rho)*Gamma(alpha, -L_0, -L_1)'
# f^a_{b,c} antisymmetric in b,c; A_mu^a no symmetry
# f^c_{d a} * f_{c e b} * A_mu^d * A_nu^a * A^{nu e} * A^{mu b}
# g = [8,11,5, 9,13,7, 1,10, 3,4, 2,12, 0,6, 14,15]
# T_c = -f^{a b c} * f_a^{d e} * A^mu_b * A_{mu d} * A^nu_c * A_{nu e}
Flavor = TensorIndexType('Flavor', dummy_fmt='F')
a, b, c, d, e, ff = tensor_indices('a,b,c,d,e,f', Flavor)
mu, nu = tensor_indices('mu,nu', Lorentz)
sym_f = tensorsymmetry([1], [2])
S_f = TensorType([Flavor] * 3, sym_f)
sym_A = tensorsymmetry([1], [1])
S_A = TensorType([Lorentz, Flavor], sym_A)
f = S_f('f')
A = S_A('A')
t = f(c, -d, -a) * f(-c, -e, -b) * A(-mu, d) * A(-nu, a) * A(nu, e) * A(
mu, b)
tc = t.canon_bp()
assert str(
tc
) == '-f(F_0, F_1, F_2)*f(-F_0, F_3, F_4)*A(L_0, -F_1)*A(-L_0, -F_3)*A(L_1, -F_2)*A(-L_1, -F_4)'
def __new__(cls, dim=4, eps_dim=4):
key = (dim, eps_dim)
if key in GammaMatrixHead._gmhd:
return GammaMatrixHead._gmhd[key]
lorentz = _LorentzContainer(*key)
gmh = TensorHead.__new__(cls, "gamma", TensorType(Tuple(lorentz, DiracSpinorIndex, DiracSpinorIndex), tensorsymmetry([1], [1], [1])), comm=2, matrix_behavior=True)
GammaMatrixHead._gmhd[key] = gmh
gmh.LorentzIndex = lorentz
return gmh
def test_canonicalize1():
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
a, a0, a1, a2, a3, b, d0, d1, d2, d3 = \
tensor_indices('a,a0,a1,a2,a3,b,d0,d1,d2,d3', Lorentz)
sym1 = tensorsymmetry([1])
base3, gens3 = get_symmetric_group_sgs(3)
sym2 = tensorsymmetry([1]*2)
sym2a = tensorsymmetry([2])
sym3 = tensorsymmetry([1]*3)
sym3a = tensorsymmetry([3])
# A_d0*A^d0; ord = [d0,-d0]
# T_c = A^d0*A_d0
S1 = TensorType([Lorentz], sym1)
A = S1('A')
t = A(-d0)*A(d0)
tc = t.canon_bp()
assert str(tc) == 'A(L_0)*A(-L_0)'
# A commuting
# A_d0*A_d1*A_d2*A^d2*A^d1*A^d0
# T_c = A^d0*A_d0*A^d1*A_d1*A^d2*A_d2
t = A(-d0)*A(-d1)*A(-d2)*A(d2)*A(d1)*A(d0)
tc = t.canon_bp()
assert str(tc) == 'A(L_0)*A(-L_0)*A(L_1)*A(-L_1)*A(L_2)*A(-L_2)'
# A anticommuting
# A_d0*A_d1*A_d2*A^d2*A^d1*A^d0
# T_c 0
A = S1('A', 1)
t = A(-d0)*A(-d1)*A(-d2)*A(d2)*A(d1)*A(d0)
tc = t.canon_bp()
assert tc == 0
# A commuting symmetric
# A^{d0 b}*A^a_d1*A^d1_d0
# T_c = A^{a d0}*A^{b d1}*A_{d0 d1}
S2 = TensorType([Lorentz]*2, sym2)
A = S2('A')
t = A(d0, b)*A(a, -d1)*A(d1, -d0)
tc = t.canon_bp()
assert str(tc) == 'A(a, L_0)*A(b, L_1)*A(-L_0, -L_1)'
# A, B commuting symmetric
# A^{d0 b}*A^d1_d0*B^a_d1
# T_c = A^{b d0}*A_d0^d1*B^a_d1
B = S2('B')
t = A(d0, b)*A(d1, -d0)*B(a, -d1)
tc = t.canon_bp()
assert str(tc) == 'A(b, L_0)*A(-L_0, L_1)*B(a, -L_1)'
# A commuting symmetric
# A^{d1 d0 b}*A^{a}_{d1 d0}; ord=[a,b, d0,-d0,d1,-d1]
# T_c = A^{a d0 d1}*A^{b}_{d0 d1}
S3 = TensorType([Lorentz]*3, sym3)
A = S3('A')
t = A(d1, d0, b)*A(a, -d1, -d0)
tc = t.canon_bp()
assert str(tc) == 'A(a, L_0, L_1)*A(b, -L_0, -L_1)'
# A^{d3 d0 d2}*A^a0_{d1 d2}*A^d1_d3^a1*A^{a2 a3}_d0
# T_c = A^{a0 d0 d1}*A^a1_d0^d2*A^{a2 a3 d3}*A_{d1 d2 d3}
t = A(d3, d0, d2)*A(a0, -d1, -d2)*A(d1, -d3, a1)*A(a2, a3, -d0)
tc = t.canon_bp()
assert str(tc) == 'A(a0, L_0, L_1)*A(a1, -L_0, L_2)*A(a2, a3, L_3)*A(-L_1, -L_2, -L_3)'
# A commuting symmetric, B antisymmetric
# A^{d0 d1 d2} * A_{d2 d3 d1} * B_d0^d3
# in this esxample and in the next three,
# renaming dummy indices and using symmetry of A,
# T = A^{d0 d1 d2} * A_{d0 d1 d3} * B_d2^d3
# can = 0
S2a = TensorType([Lorentz]*2, sym2a)
A = S3('A')
B = S2a('B')
t = A(d0, d1, d2)*A(-d2, -d3, -d1)*B(-d0, d3)
tc = t.canon_bp()
assert tc == 0
# A anticommuting symmetric, B anticommuting
# A^{d0 d1 d2} * A_{d2 d3 d1} * B_d0^d3
# T_c = A^{d0 d1 d2} * A_{d0 d1}^d3 * B_{d2 d3}
A = S3('A', 1)
B = S2a('B')
t = A(d0, d1, d2)*A(-d2, -d3, -d1)*B(-d0, d3)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1, L_2)*A(-L_0, -L_1, L_3)*B(-L_2, -L_3)'
# A anticommuting symmetric, B antisymmetric commuting, antisymmetric metric
# A^{d0 d1 d2} * A_{d2 d3 d1} * B_d0^d3
# T_c = -A^{d0 d1 d2} * A_{d0 d1}^d3 * B_{d2 d3}
Spinor = TensorIndexType('Spinor', metric=1, dummy_fmt='S')
a, a0, a1, a2, a3, b, d0, d1, d2, d3 = \
tensor_indices('a,a0,a1,a2,a3,b,d0,d1,d2,d3', Spinor)
S3 = TensorType([Spinor]*3, sym3)
S2a = TensorType([Spinor]*2, sym2a)
A = S3('A', 1)
B = S2a('B')
t = A(d0, d1, d2)*A(-d2, -d3, -d1)*B(-d0, d3)
tc = t.canon_bp()
assert str(tc) == '-A(S_0, S_1, S_2)*A(-S_0, -S_1, S_3)*B(-S_2, -S_3)'
# A anticommuting symmetric, B antisymmetric anticommuting,
# no metric symmetry
# A^{d0 d1 d2} * A_{d2 d3 d1} * B_d0^d3
# T_c = A^{d0 d1 d2} * A_{d0 d1 d3} * B_d2^d3
Mat = TensorIndexType('Mat', metric=None, dummy_fmt='M')
a, a0, a1, a2, a3, b, d0, d1, d2, d3 = \
tensor_indices('a,a0,a1,a2,a3,b,d0,d1,d2,d3', Mat)
S3 = TensorType([Mat]*3, sym3)
S2a = TensorType([Mat]*2, sym2a)
A = S3('A', 1)
B = S2a('B')
t = A(d0, d1, d2)*A(-d2, -d3, -d1)*B(-d0, d3)
tc = t.canon_bp()
assert str(tc) == 'A(M_0, M_1, M_2)*A(-M_0, -M_1, -M_3)*B(-M_2, M_3)'
# Gamma anticommuting
# Gamma_{mu nu} * gamma^rho * Gamma^{nu mu alpha}
# T_c = -Gamma^{mu nu} * gamma^rho * Gamma_{alpha mu nu}
S1 = TensorType([Lorentz], sym1)
S2a = TensorType([Lorentz]*2, sym2a)
S3a = TensorType([Lorentz]*3, sym3a)
alpha, beta, gamma, mu, nu, rho = \
tensor_indices('alpha,beta,gamma,mu,nu,rho', Lorentz)
Gamma = S1('Gamma', 2)
Gamma2 = S2a('Gamma', 2)
Gamma3 = S3a('Gamma', 2)
t = Gamma2(-mu,-nu)*Gamma(rho)*Gamma3(nu, mu, alpha)
tc = t.canon_bp()
assert str(tc) == '-Gamma(L_0, L_1)*Gamma(rho)*Gamma(alpha, -L_0, -L_1)'
# Gamma_{mu nu} * Gamma^{gamma beta} * gamma_rho * Gamma^{nu mu alpha}
# T_c = Gamma^{mu nu} * Gamma^{beta gamma} * gamma_rho * Gamma^alpha_{mu nu}
t = Gamma2(mu, nu)*Gamma2(beta, gamma)*Gamma(-rho)*Gamma3(alpha, -mu, -nu)
tc = t.canon_bp()
assert str(tc) == 'Gamma(L_0, L_1)*Gamma(beta, gamma)*Gamma(-rho)*Gamma(alpha, -L_0, -L_1)'
# f^a_{b,c} antisymmetric in b,c; A_mu^a no symmetry
# f^c_{d a} * f_{c e b} * A_mu^d * A_nu^a * A^{nu e} * A^{mu b}
# g = [8,11,5, 9,13,7, 1,10, 3,4, 2,12, 0,6, 14,15]
# T_c = -f^{a b c} * f_a^{d e} * A^mu_b * A_{mu d} * A^nu_c * A_{nu e}
Flavor = TensorIndexType('Flavor', dummy_fmt='F')
a, b, c, d, e, ff = tensor_indices('a,b,c,d,e,f', Flavor)
mu, nu = tensor_indices('mu,nu', Lorentz)
sym_f = tensorsymmetry([1], [2])
S_f = TensorType([Flavor]*3, sym_f)
sym_A = tensorsymmetry([1], [1])
S_A = TensorType([Lorentz, Flavor], sym_A)
f = S_f('f')
A = S_A('A')
t = f(c, -d, -a)*f(-c, -e, -b)*A(-mu, d)*A(-nu, a)*A(nu, e)*A(mu, b)
tc = t.canon_bp()
assert str(tc) == '-f(F_0, F_1, F_2)*f(-F_0, F_3, F_4)*A(L_0, -F_1)*A(-L_0, -F_3)*A(L_1, -F_2)*A(-L_1, -F_4)'
def test_canonicalize_no_slot_sym():
# A_d0 * B^d0; T_c = A^d0*B_d0
Lorentz = TensorIndexType('Lorentz', dummy_fmt='L')
a, b, d0, d1 = tensor_indices('a,b,d0,d1', Lorentz)
sym1 = tensorsymmetry([1])
S1 = TensorType([Lorentz], sym1)
A, B = S1('A,B')
t = A(-d0)*B(d0)
tc = t.canon_bp()
assert str(tc) == 'A(L_0)*B(-L_0)'
# A^a * B^b; T_c = T
t = A(a)*B(b)
tc = t.canon_bp()
assert tc == t
# B^b * A^a
t1 = B(b)*A(a)
tc = t1.canon_bp()
assert str(tc) == 'A(a)*B(b)'
# A symmetric
# A^{b}_{d0}*A^{d0, a}; T_c = A^{a d0}*A{b}_{d0}
sym2 = tensorsymmetry([1]*2)
S2 = TensorType([Lorentz]*2, sym2)
A = S2('A')
t = A(b, -d0)*A(d0, a)
tc = t.canon_bp()
assert str(tc) == 'A(a, L_0)*A(b, -L_0)'
# A^{d1}_{d0}*B^d0*C_d1
# T_c = A^{d0 d1}*B_d0*C_d1
B, C = S1('B,C')
t = A(d1, -d0)*B(d0)*C(-d1)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1)*B(-L_0)*C(-L_1)'
# A without symmetry
# A^{d1}_{d0}*B^d0*C_d1 ord=[d0,-d0,d1,-d1]; g = [2,1,0,3,4,5]
# T_c = A^{d0 d1}*B_d1*C_d0; can = [0,2,3,1,4,5]
nsym2 = tensorsymmetry([1],[1])
NS2 = TensorType([Lorentz]*2, nsym2)
A = NS2('A')
B, C = S1('B, C')
t = A(d1, -d0)*B(d0)*C(-d1)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1)*B(-L_1)*C(-L_0)'
# A, B without symmetry
# A^{d1}_{d0}*B_{d1}^{d0}
# T_c = A^{d0 d1}*B_{d0 d1}
B = NS2('B')
t = A(d1, -d0)*B(-d1, d0)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1)*B(-L_0, -L_1)'
# A_{d0}^{d1}*B_{d1}^{d0}
# T_c = A^{d0 d1}*B_{d1 d0}
t = A(-d0, d1)*B(-d1, d0)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1)*B(-L_1, -L_0)'
# A, B, C without symmetry
# A^{d1 d0}*B_{a d0}*C_{d1 b}
# T_c=A^{d0 d1}*B_{a d1}*C_{d0 b}
C = NS2('C')
t = A(d1, d0)*B(-a, -d0)*C(-d1, -b)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1)*B(-a, -L_1)*C(-L_0, -b)'
# A symmetric, B and C without symmetry
# A^{d1 d0}*B_{a d0}*C_{d1 b}
# T_c = A^{d0 d1}*B_{a d0}*C_{d1 b}
A = S2('A')
t = A(d1, d0)*B(-a, -d0)*C(-d1, -b)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1)*B(-a, -L_0)*C(-L_1, -b)'
# A and C symmetric, B without symmetry
# A^{d1 d0}*B_{a d0}*C_{d1 b} ord=[a,b,d0,-d0,d1,-d1]
# T_c = A^{d0 d1}*B_{a d0}*C_{b d1}
C = S2('C')
t = A(d1, d0)*B(-a, -d0)*C(-d1, -b)
tc = t.canon_bp()
assert str(tc) == 'A(L_0, L_1)*B(-a, -L_0)*C(-b, -L_1)'
