Environment to perform calculations of equivariant vector bundles on homogeneous varieties
License: GPL3
ubuntu2204
Kernel: SageMath 9.8
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X: Orthogonal grassmannian variety of 3-dimensional isotropic linear subspaces in a 9-dimensional ambient vector space.
(n=4)
Dimension: 12
Rank of K0(X) (max. collection length): 32
Fano index (max. orbit length): 5
Consecutive Lefschetz collection.
Starting block:
1 VB(0)
2 VB(Lambda[1])
3 VB(Lambda[2])
4 VB(Lambda[4])
5 Equivariant extension of VB(Lambda[1] + Lambda[4]) by VB(Lambda[4])
6 Equivariant extension of VB(2*Lambda[1] + Lambda[4]) by VB(Lambda[1] + Lambda[4])
Alternating Lefschetz collection.
Starting block:
1 VB(0)
2 VB(Lambda[4])
3 VB(Lambda[1])
4 VB(Lambda[2])
5 Equivariant extension of VB(Lambda[1] + Lambda[4]) by VB(Lambda[4])
6 Equivariant extension of VB(2*Lambda[1] + Lambda[4]) by VB(Lambda[1] + Lambda[4])
Gap.
lMax-l = 5
(lMax-l)/wMax = 1
Try to fill the gap.
Semi-simplification is VB(Lambda[2] - Lambda[3] + 2*Lambda[4]) + VB(Lambda[2]) + VB(Lambda[1]) + VB(2*Lambda[4]) + VB(Lambda[3]).
Can candidate be embedded in the Lefschetz collection LC1?
Not after row 0.
Not after row 1.
Not after row 2.
Not after row 3.
Yes after row 4 to the columns [0, 1, 2, 3, 4].
Yes after row 5 to the columns [0, 1, 2, 3, 4].
Yes after row 6 to the columns [0, 1, 2, 3, 4].
Can candidate be embedded in the Lefschetz collection LC2?
Not after row 0.
Not after row 1.
Not after row 2.
Not after row 3.
Yes after row 4 to the columns [0, 1, 2, 3, 4].
Yes after row 5 to the columns [0, 1, 2, 3, 4].
Yes after row 6 to the columns [0, 1, 2, 3, 4].
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{2: 2*B4(0,0,0,0) + B4(1,0,0,0), 1: 5*B4(0,0,0,0) + 2*B4(1,0,0,0), 0: 2*B4(0,0,0,0) + B4(1,0,0,0)}
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X: Orthogonal grassmannian variety of 3-dimensional isotropic linear subspaces in a 9-dimensional ambient vector space.
(n=4)
Initialise suitable objects:
- Repesentations
- Tautological bundles
- Spinor bundles
Initialise Lefschetz collection:
0 VB(0)
1 VB(Lambda[1])
2 VB(Lambda[2])
3 VB(Lambda[4])
4 Equivariant extension of VB(Lambda[1] + Lambda[4]) by VB(Lambda[4])
5 Equivariant extension of VB(2*Lambda[1] + Lambda[4]) by VB(Lambda[1] + Lambda[4])
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Equivariant extension of VB(Lambda[1] - Lambda[3] + 2*Lambda[4]) by VB(-Lambda[3] + 2*Lambda[4]) + VB(0)
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{2: 2*B4(0,0,0,0) + B4(1,0,0,0), 1: B4(0,0,0,0)}
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On the sequence 0 -> cE -> ... -> cE(4) -> 0 where cE = cU(fw[1]+fw[2])
EXT( cE(4) , cE ) = {9: B4(0,0,0,0)}
Initialise the left side.
Initialise the right side.
Compute EXTs from B[-1][*] to A[1][*]:
Objects:
B[-1][0] = Kernel
B[-1][1] = B4(1,0,0,0) * VB(2*Lambda[2] + 2*Lambda[3]) + 2*B4(1,0,0,0) * VB(Lambda[2] + 2*Lambda[3] + 2*Lambda[4]) + B4(1,0,0,0) * VB(2*Lambda[3] + 4*Lambda[4]) + B4(1,0,0,0) * VB(4*Lambda[3]) + B4(1,0,0,0) * VB(Lambda[1] + 3*Lambda[3]) + B4(1,0,0,0) * VB(3*Lambda[3] + 2*Lambda[4])
B[-1][2] = ( B4(0,0,0,0) + B4(0,1,0,0) + B4(2,0,0,0) ) * VB(Lambda[2] + 3*Lambda[3]) + ( B4(0,0,0,0) + B4(0,1,0,0) + B4(2,0,0,0) ) * VB(3*Lambda[3] + 2*Lambda[4])
B[-1][3] = B4(1,1,0,0) * VB(4*Lambda[3])
B[-1][4] = VB(Lambda[1] + Lambda[2] + 4*Lambda[3])
A[1][-4] = VB(Lambda[1] + Lambda[2])
A[1][-3] = B4(1,0,0,0) * VB(2*Lambda[2]) + B4(1,0,0,0) * VB(Lambda[1] + Lambda[3])
A[1][-2] = ( B4(0,0,0,0) + B4(0,1,0,0) + B4(2,0,0,0) ) * VB(Lambda[2] + Lambda[3])
A[1][-1] = B4(1,1,0,0) * VB(2*Lambda[3])
A[1][0] = Cokernel
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On the sequence 0 -> cS_y -> ... -> cS_y(l_y) -> 0 whenever cS_y is from the starting block of the spinor collection
------------------------------------------------------------------------------------------------------------------------------------------------------
cS_y = VB(Lambda[4]) with l_y = 5
(y=0)
Initialise the left side.
Initialise the right side.
Construction of A´s:
Counter=1:
Complex:
... --d_-3--> 0 --d_-2--> VB(Lambda[4]) --d_-1--> VB(Lambda[4]) --d_0--> 0 --d_1--> ...
Is complex numerically exact? True
Construction of B´s:
Counter=-1:
Complex:
... --d_-2--> 0 --d_-1--> Kernel --d_0--> B4(0,0,0,1) * VB(5*Lambda[3]) --d_1--> VB(5*Lambda[3] + Lambda[4]) --d_2--> 0 --d_3--> ...
Is complex numerically exact? True
Compute EXTs from B[-1][*] to A[1][*]:
Objects:
B[-1][0] = Kernel
B[-1][1] = B4(0,0,0,1) * VB(5*Lambda[3])
B[-1][2] = VB(5*Lambda[3] + Lambda[4])
A[1][-1] = VB(Lambda[4])
A[1][0] = VB(Lambda[4])
| A[1][-1] A[1][0]
+----------+-------------------+-------------------+
B[-1][0] | ... ...
B[-1][1] | {} {}
B[-1][2] | {12: B4(0,0,0,0)} {12: B4(0,0,0,0)}
------------------------------------------------------------------------------------------------------------------------------------------------------
cS_y = Equivariant extension of VB(Lambda[1] + Lambda[4]) by VB(Lambda[4]) with l_y = 5
(y=1)
Initialise the left side.
Initialise the right side.
Construction of A´s:
Counter=1:
Complex:
... --d_-4--> 0 --d_-3--> Equivariant extension of VB(Lambda[1] + Lambda[4]) by VB(Lambda[4]) --d_-2--> B4(0,0,0,1) * VB(Lambda[3]) --d_-1--> Equivariant extension of VB(Lambda[3] + Lambda[4]) by VB(Lambda[2] + Lambda[4]) --d_0--> 0 --d_1--> ...
Is complex numerically exact? True
Construction of B´s:
Counter=-1:
Complex:
... --d_-2--> 0 --d_-1--> Kernel --d_0--> ( B4(0,0,0,0) + B4(1,0,0,0) ) * VB(5*Lambda[3] + Lambda[4]) --d_1--> Equivariant extension of VB(Lambda[1] + 5*Lambda[3] + Lambda[4]) by VB(5*Lambda[3] + Lambda[4]) --d_2--> 0 --d_3--> ...
Is complex numerically exact? True
Compute EXTs from B[-1][*] to A[1][*]:
Objects:
B[-1][0] = Kernel
B[-1][1] = ( B4(0,0,0,0) + B4(1,0,0,0) ) * VB(5*Lambda[3] + Lambda[4])
B[-1][2] = Equivariant extension of VB(Lambda[1] + 5*Lambda[3] + Lambda[4]) by VB(5*Lambda[3] + Lambda[4])
A[1][-2] = Equivariant extension of VB(Lambda[1] + Lambda[4]) by VB(Lambda[4])
A[1][-1] = B4(0,0,0,1) * VB(Lambda[3])
A[1][0] = Equivariant extension of VB(Lambda[3] + Lambda[4]) by VB(Lambda[2] + Lambda[4])
| A[1][-2] A[1][-1] A[1][0]
+----------+------------------------------------------------------------------+----------+-------------------+
B[-1][0] | ... ... ...
B[-1][1] | {11: B4(0,0,0,0) + B4(1,0,0,0), 12: B4(0,0,0,0) + B4(1,0,0,0)} {} {}
B[-1][2] | {11: B4(0,0,0,0) + B4(1,0,0,0), 12: 2*B4(0,0,0,0) + B4(1,0,0,0)} {} {11: B4(0,0,0,0)}
------------------------------------------------------------------------------------------------------------------------------------------------------
cS_y = Equivariant extension of VB(2*Lambda[1] + Lambda[4]) by VB(Lambda[1] + Lambda[4]) with l_y = 2
(y=2)
Initialise the left side.
Initialise the right side.
Construction of A´s:
Counter=1:
Complex:
... --d_-5--> 0 --d_-4--> Equivariant extension of VB(2*Lambda[1] + Lambda[4]) by VB(Lambda[1] + Lambda[4]) --d_-3--> B4(0,0,0,1) * VB(Lambda[1] + Lambda[3]) --d_-2--> B4(0,0,0,1) * VB(Lambda[2] + Lambda[3]) --d_-1--> Equivariant extension of VB(Lambda[2] + Lambda[3] + Lambda[4]) by VB(2*Lambda[2] + Lambda[4]) --d_0--> 0 --d_1--> ...
Is complex numerically exact? True
Construction of B´s:
Counter=-1:
Complex:
... --d_-2--> 0 --d_-1--> Kernel --d_0--> Equivariant extension of ( B4(0,0,0,0) + B4(1,0,0,0) ) * VB(Lambda[1] + 2*Lambda[3] + Lambda[4]) by ( B4(0,0,0,0) + B4(1,0,0,0) ) * VB(2*Lambda[3] + Lambda[4]) --d_1--> Equivariant extension of VB(2*Lambda[1] + 2*Lambda[3] + Lambda[4]) by VB(Lambda[1] + 2*Lambda[3] + Lambda[4]) --d_2--> 0 --d_3--> ...
Is complex numerically exact? True
Compute EXTs from B[-1][*] to A[1][*]:
Objects:
B[-1][0] = Kernel
B[-1][1] = Equivariant extension of ( B4(0,0,0,0) + B4(1,0,0,0) ) * VB(Lambda[1] + 2*Lambda[3] + Lambda[4]) by ( B4(0,0,0,0) + B4(1,0,0,0) ) * VB(2*Lambda[3] + Lambda[4])
B[-1][2] = Equivariant extension of VB(2*Lambda[1] + 2*Lambda[3] + Lambda[4]) by VB(Lambda[1] + 2*Lambda[3] + Lambda[4])
A[1][-3] = Equivariant extension of VB(2*Lambda[1] + Lambda[4]) by VB(Lambda[1] + Lambda[4])
A[1][-2] = B4(0,0,0,1) * VB(Lambda[1] + Lambda[3])
A[1][-1] = B4(0,0,0,1) * VB(Lambda[2] + Lambda[3])
A[1][0] = Equivariant extension of VB(Lambda[2] + Lambda[3] + Lambda[4]) by VB(2*Lambda[2] + Lambda[4])
| A[1][-3] A[1][-2] A[1][-1] A[1][0]
+----------+------------------+----------+----------+------------------------------------------------------------------------------------------------+
B[-1][0] | ... ... ... ...
B[-1][1] | {} {} {} {2: 2*B4(0,0,0,0) + 2*B4(1,0,0,0), 3: B4(0,0,0,0) + B4(1,0,0,0), 1: B4(0,0,0,0) + B4(1,0,0,0)}
B[-1][2] | {5: B4(0,0,0,0)} {} {} {3: 2*B4(0,0,0,0), 2: B4(0,0,0,0)}
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VB(2*Lambda[1] + Lambda[3] + 2*Lambda[4]) + VB(Lambda[1] + 4*Lambda[4]) + VB(Lambda[2] + Lambda[3] + 2*Lambda[4]) + VB(Lambda[1] + Lambda[3] + 2*Lambda[4]) + VB(Lambda[1] + Lambda[2] + 2*Lambda[3]) + VB(4*Lambda[4])
---------------------------------------------------------------------------
KeyError Traceback (most recent call last)
Cell In [27], line 2
1 print( cA[Integer(1)].SemiSimplification(Integer(0)) )
----> 2 print( cB[-Integer(1)].SemiSimplification(Integer(0)) )
KeyError: -1
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On the sequence 0 -> P -> ... -> P(5) -> 0
Construction of K´s:
Counter=1:
Complex:
... --d_-4--> 0 --d_-3--> Equivariant extension of VB(Lambda[2]) + VB(Lambda[1] - Lambda[3] + 2*Lambda[4]) + VB(-Lambda[3] + 2*Lambda[4]) by VB(0) --d_-2--> B4(0,0,0,1) * VB(Lambda[3] + Lambda[4]) --d_-1--> Cokernel --d_0--> 0 --d_1--> ...
Is complex numerically exact? False
Construction of L´s:
Counter=-1:
Complex:
... --d_-2--> 0 --d_-1--> Kernel --d_0--> Equivariant extension of VB(Lambda[2] + 5*Lambda[3]) + VB(Lambda[1] + 4*Lambda[3] + 2*Lambda[4]) + VB(4*Lambda[3] + 2*Lambda[4]) by VB(5*Lambda[3]) --d_1--> 0 --d_2--> ...
Is complex numerically exact? True
Compute EXTs from L[-1][*] to L[1][*]:
Objects:
L[-1][0] = Kernel
L[-1][1] = Equivariant extension of VB(Lambda[2] + 5*Lambda[3]) + VB(Lambda[1] + 4*Lambda[3] + 2*Lambda[4]) + VB(4*Lambda[3] + 2*Lambda[4]) by VB(5*Lambda[3])
K[-1][-2] = Equivariant extension of VB(Lambda[2]) + VB(Lambda[1] - Lambda[3] + 2*Lambda[4]) + VB(-Lambda[3] + 2*Lambda[4]) by VB(0)
K[-1][-1] = B4(0,0,0,1) * VB(Lambda[3] + Lambda[4])
K[-1][0] = Cokernel
| K[1][-2] K[1][-1] K[1][0]
+----------+------------------------------------------------------------------------------------------------+----------+---------+
L[-1][0] | ... ... ...
L[-1][1] | {12: 4*B4(0,0,0,0) + B4(1,0,0,0) + B4(0,1,0,0), 11: 3*B4(0,0,0,0) + B4(1,0,0,0) + B4(0,1,0,0)} {} ...
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