Macaulay2 » Documentation
Packages » MonomialIntegerPrograms :: bettiTablesWithHilbertFunction
next | previous | forward | backward | up | index | toc

bettiTablesWithHilbertFunction -- list or tally all Betti tables that can be obtained from monomial ideals with a particular (partial or complete) Hilbert function

Synopsis

Description

This function calls monomialIdealsWithHilbertFunction with the specified options, determines the Betti table of each feasible monomial ideal, then lists or tallies the Betti tables encountered. The Count option does not fundamentally change how the computation is performed, only how the results are reported.

i1 : R = QQ[x,y,z]; L = {1, 3, 5, 5, 4};
i3 : bettiTablesWithHilbertFunction(L, R) --outputs unique tables matching the criteria

             0 1 2 3         0 1 2 3         0 1 2 3         0 1 2 3        
o3 = {total: 1 4 4 1, total: 1 4 4 1, total: 1 4 4 1, total: 1 3 3 1, total:
          0: 1 . . .      0: 1 . . .      0: 1 . . .      0: 1 . . .      0:
          1: . 1 . .      1: . 1 . .      1: . 1 . .      1: . 1 . .      1:
          2: . 2 2 .      2: . 2 2 .      2: . 2 2 .      2: . 2 1 .      2:
          3: . 1 2 1      3: . 1 1 .      3: . 1 . .      3: . . 2 1      3:
                          4: . . 1 1      4: . . 2 .                      4:
                                          5: . . . 1                        
                                                                            
     ------------------------------------------------------------------------
     0 1 2 3         0 1 2 3         0 1 2 3         0 1 2 3         0 1 2 3 
     1 4 5 2, total: 1 4 5 2, total: 1 3 3 1, total: 1 5 6 2, total: 1 5 6 2,
     1 . . .      0: 1 . . .      0: 1 . . .      0: 1 . . .      0: 1 . . . 
     . 1 . .      1: . 1 . .      1: . 1 . .      1: . 1 . .      1: . 1 . . 
     . 2 2 .      2: . 2 2 .      2: . 2 1 .      2: . 2 3 1      2: . 2 3 1 
     . 1 . .      3: . 1 . .      3: . . 1 .      3: . 2 3 1      3: . 2 2 . 
     . . 3 2      4: . . 1 .      4: . . 1 1                      4: . . 1 1 
                  5: . . 2 2                                                 
                                                                             
     ------------------------------------------------------------------------
            0 1 2 3         0 1 2 3         0 1 2 3         0 1 2 3         0
     total: 1 5 6 2, total: 1 5 7 3, total: 1 5 7 3, total: 1 5 7 3, total: 1
         0: 1 . . .      0: 1 . . .      0: 1 . . .      0: 1 . . .      0: 1
         1: . 1 . .      1: . 1 . .      1: . 1 . .      1: . 1 . .      1: .
         2: . 2 3 1      2: . 2 3 1      2: . 2 3 1      2: . 2 3 1      2: .
         3: . 2 2 .      3: . 2 1 .      3: . 2 1 .      3: . 2 1 .      3: .
         4: . . . .      4: . . 2 1      4: . . 3 2      4: . . 2 1      4: .
         5: . . 1 1      5: . . 1 1                      5: . . . .      5: .
                                                         6: . . 1 1          
     ------------------------------------------------------------------------
     1 2 3         0 1 2 3         0 1 2 3
     4 5 2, total: 1 5 6 2, total: 1 4 4 1}
     . . .      0: 1 . . .      0: 1 . . .
     1 . .      1: . 1 . .      1: . 1 . .
     2 2 .      2: . 2 3 1      2: . 2 2 .
     1 . .      3: . 2 2 .      3: . 1 1 .
     . 2 1      4: . . . .      4: . . . .
     . 1 1      5: . . . .      5: . . 1 1
                6: . . 1 1

o3 : List
i4 : bettiTablesWithHilbertFunction(L, R, Count => true) --tallies distinct ideals giving each table

                  0 1 2 3
o4 = Tally{total: 1 3 3 1 => 12 }
               0: 1 . . .
               1: . 1 . .
               2: . 2 1 .
               3: . . 1 .
               4: . . 1 1
                  0 1 2 3
           total: 1 3 3 1 => 27
               0: 1 . . .
               1: . 1 . .
               2: . 2 1 .
               3: . . 2 1
                  0 1 2 3
           total: 1 4 4 1 => 6
               0: 1 . . .
               1: . 1 . .
               2: . 2 2 .
               3: . 1 . .
               4: . . 2 .
               5: . . . 1
                  0 1 2 3
           total: 1 4 4 1 => 12
               0: 1 . . .
               1: . 1 . .
               2: . 2 2 .
               3: . 1 1 .
               4: . . . .
               5: . . 1 1
                  0 1 2 3
           total: 1 4 4 1 => 78
               0: 1 . . .
               1: . 1 . .
               2: . 2 2 .
               3: . 1 1 .
               4: . . 1 1
                  0 1 2 3
           total: 1 4 4 1 => 174
               0: 1 . . .
               1: . 1 . .
               2: . 2 2 .
               3: . 1 2 1
                  0 1 2 3
           total: 1 4 5 2 => 6
               0: 1 . . .
               1: . 1 . .
               2: . 2 2 .
               3: . 1 . .
               4: . . 2 1
               5: . . 1 1
                  0 1 2 3
           total: 1 4 5 2 => 9
               0: 1 . . .
               1: . 1 . .
               2: . 2 2 .
               3: . 1 . .
               4: . . 1 .
               5: . . 2 2
                  0 1 2 3
           total: 1 4 5 2 => 15
               0: 1 . . .
               1: . 1 . .
               2: . 2 2 .
               3: . 1 . .
               4: . . 3 2
                  0 1 2 3
           total: 1 5 6 2 => 6
               0: 1 . . .
               1: . 1 . .
               2: . 2 3 1
               3: . 2 2 .
               4: . . . .
               5: . . . .
               6: . . 1 1
                  0 1 2 3
           total: 1 5 6 2 => 24
               0: 1 . . .
               1: . 1 . .
               2: . 2 3 1
               3: . 2 2 .
               4: . . . .
               5: . . 1 1
                  0 1 2 3
           total: 1 5 6 2 => 54
               0: 1 . . .
               1: . 1 . .
               2: . 2 3 1
               3: . 2 2 .
               4: . . 1 1
                  0 1 2 3
           total: 1 5 6 2 => 150
               0: 1 . . .
               1: . 1 . .
               2: . 2 3 1
               3: . 2 3 1
                  0 1 2 3
           total: 1 5 7 3 => 12
               0: 1 . . .
               1: . 1 . .
               2: . 2 3 1
               3: . 2 1 .
               4: . . 2 1
               5: . . . .
               6: . . 1 1
                  0 1 2 3
           total: 1 5 7 3 => 12
               0: 1 . . .
               1: . 1 . .
               2: . 2 3 1
               3: . 2 1 .
               4: . . 2 1
               5: . . 1 1
                  0 1 2 3
           total: 1 5 7 3 => 12
               0: 1 . . .
               1: . 1 . .
               2: . 2 3 1
               3: . 2 1 .
               4: . . 3 2

o4 : Tally
i5 : bettiTablesWithHilbertFunction(L, R, FirstBetti => 5) --only returns tables whose first total betti number is 5

             0 1 2 3         0 1 2 3         0 1 2 3         0 1 2 3        
o5 = {total: 1 5 6 2, total: 1 5 6 2, total: 1 5 6 2, total: 1 5 6 2, total:
          0: 1 . . .      0: 1 . . .      0: 1 . . .      0: 1 . . .      0:
          1: . 1 . .      1: . 1 . .      1: . 1 . .      1: . 1 . .      1:
          2: . 2 3 1      2: . 2 3 1      2: . 2 3 1      2: . 2 3 1      2:
          3: . 2 3 1      3: . 2 2 .      3: . 2 2 .      3: . 2 2 .      3:
                          4: . . 1 1      4: . . . .      4: . . . .      4:
                                          5: . . 1 1      5: . . . .        
                                                          6: . . 1 1        
     ------------------------------------------------------------------------
     0 1 2 3         0 1 2 3         0 1 2 3
     1 5 7 3, total: 1 5 7 3, total: 1 5 7 3}
     1 . . .      0: 1 . . .      0: 1 . . .
     . 1 . .      1: . 1 . .      1: . 1 . .
     . 2 3 1      2: . 2 3 1      2: . 2 3 1
     . 2 1 .      3: . 2 1 .      3: . 2 1 .
     . . 3 2      4: . . 2 1      4: . . 2 1
                  5: . . . .      5: . . 1 1
                  6: . . 1 1

o5 : List
i6 : bettiTablesWithHilbertFunction(L, R, GradedBettis => {0, 0, 2, 2, 1}) --only returns tables whose first graded betti numbers match a given sequence

o6 = {}

o6 : List
i7 : bettiTablesWithHilbertFunction(L, R, BoundGenerators => 3)

             0 1 2 3         0 1 2 3
o7 = {total: 1 3 3 1, total: 1 3 3 1}
          0: 1 . . .      0: 1 . . .
          1: . 1 . .      1: . 1 . .
          2: . 2 1 .      2: . 2 1 .
          3: . . 2 1      3: . . 1 .
                          4: . . 1 1

o7 : List
i8 : bettiTablesWithHilbertFunction(L, R, BoundGenerators => 3, Count => true)

                  0 1 2 3
o8 = Tally{total: 1 3 3 1 => 12}
               0: 1 . . .
               1: . 1 . .
               2: . 2 1 .
               3: . . 1 .
               4: . . 1 1
                  0 1 2 3
           total: 1 3 3 1 => 27
               0: 1 . . .
               1: . 1 . .
               2: . 2 1 .
               3: . . 2 1

o8 : Tally

These methods also work for squarefree ideals

i9 : S = QQ[a..f]

o9 = S

o9 : PolynomialRing
i10 : bettiTablesWithHilbertFunction({1, 6, 19, 45, 86}, S, SquareFree => true)

              0 1 2 3
o10 = {total: 1 6 8 3}
           0: 1 . . .
           1: . 2 1 .
           2: . . . .
           3: . 4 7 3

o10 : List

The next examples show that options can be combined in many ways

i11 : bettiTablesWithHilbertFunction({1, 3, 6, 7, 6, 5, 4, 4, 4}, R, FirstBetti => 6, BoundGenerators => 5, Count => true)

                   0 1 2 3
o11 = Tally{total: 1 6 7 2 => 48 }
                0: 1 . . .
                1: . . . .
                2: . 3 3 1
                3: . 3 3 .
                4: . . . .
                5: . . 1 1
                   0 1 2 3
            total: 1 6 7 2 => 522
                0: 1 . . .
                1: . . . .
                2: . 3 2 .
                3: . 2 3 1
                4: . 1 1 .
                5: . . 1 1
                   0 1 2 3
            total: 1 6 8 3 => 12
                0: 1 . . .
                1: . . . .
                2: . 3 3 1
                3: . 3 3 1
                4: . . 1 .
                5: . . 1 1
                   0 1 2 3
            total: 1 6 8 3 => 72
                0: 1 . . .
                1: . . . .
                2: . 3 1 .
                3: . 1 4 2
                4: . 2 2 .
                5: . . 1 1

o11 : Tally
i12 : bettiTablesWithHilbertFunction({1, 4, 7, 10, 13}, S, SquareFree => true, FirstBetti => 5)

              0 1 2 3 4
o12 = {total: 1 5 9 7 2}
           0: 1 2 1 . .
           1: . 3 8 7 2

o12 : List
i13 : bettiTablesWithHilbertFunction({1, 4, 7, 10, 13}, S, SquareFree => true, GradedBettis => {0, 2, 3, 1, 0})

              0 1  2  3 4 5
o13 = {total: 1 6 13 13 6 1}
           0: 1 2  1  . . .
           1: . 3  9 10 5 1
           2: . 1  3  3 1 .

o13 : List

See also

Ways to use bettiTablesWithHilbertFunction :

For the programmer

The object bettiTablesWithHilbertFunction is a method function with options.