addFiltration replaces the filtration matrices in
E by the matrices in
the
List L. The matrices in
L must be
1 by
k
matrices over
ZZ, where
k is the rank of the vector bundle
E. The
list has to contain one matrix for each ray of the underlying fan over which
E is defined.
Note that in
E the rays are already sorted and that the filtration matrices in
L
will be assigned to the rays in that order. To see the order, use
rays(ToricVectorBundle).
"The filtration on the vector bundle over a ray is given by the filtration matrix for this
ray in the following way: The first index
j, such that the
i-th basis
vector in the basis over this ray appears in the
j-th step of the filtration, is the
i-th entry of the filtration matrix. OR in other words, the
j-th step
step in the filtration is given by all columns of the basis matrix for which the corresponding entry
in the filtration matrix is less or equal to
j."
The matrices need not satisfy the compatability condition. This can be checked
with
isVectorBundle.
i1 : E = toricVectorBundle(2,pp1ProductFan 2)
o1 = {dimension of the variety => 2 }
number of affine charts => 4
number of rays => 4
rank of the vector bundle => 2
o1 : ToricVectorBundleKlyachko
|
i2 : details E
o2 = HashTable{| -1 | => (| 1 0 |, 0)}
| 0 | | 0 1 |
| 0 | => (| 1 0 |, 0)
| -1 | | 0 1 |
| 0 | => (| 1 0 |, 0)
| 1 | | 0 1 |
| 1 | => (| 1 0 |, 0)
| 0 | | 0 1 |
o2 : HashTable
|
i3 : F = addFiltration(E,{matrix{{1,3}},matrix{{-1,3}},matrix{{2,-3}},matrix{{0,-1}}})
o3 = {dimension of the variety => 2 }
number of affine charts => 4
number of rays => 4
rank of the vector bundle => 2
o3 : ToricVectorBundleKlyachko
|
i4 : details F
o4 = HashTable{| -1 | => (| 1 0 |, | 2 -3 |)}
| 0 | | 0 1 |
| 0 | => (| 1 0 |, | 1 3 |)
| -1 | | 0 1 |
| 0 | => (| 1 0 |, | 0 -1 |)
| 1 | | 0 1 |
| 1 | => (| 1 0 |, | -1 3 |)
| 0 | | 0 1 |
o4 : HashTable
|
i5 : isVectorBundle F
o5 = true
|
This means that for example over the first ray the first basis vector of the filtration of
F
appears at the filtration step 1 and the second at 3.