LEVEL 547


GRITSENKO LIFTS
Number of wt 2 Gritsenko lifts: 20


WEIGHT 4 CUSP FORMS
The weight 4 space of cusp forms (and the plus and minus parts) have dimensions:
     dim S4(K(547)) = 597
     dim S4(K(547))+ = 478
     dim S4(K(547))- = 119
We use the following wt 4 plus forms in an attempt to fill out the wt 4 plus space of cusp forms. We computed the initial 1796 Fourier coefficients of these forms (which is up through determinant 791/4). (This of course required much longer expansions of the Fourier series before computing any Hecke operators - actually 238484 Fourier coefficients were computed.)
and the rank of these 1050 truncated series was computed mod 19 to be 478.
So these forms span at least 478 linearly independent plus forms. Hence dim S4(K(547))+ ≥ 478.

Theta tracing was used only to span the space of minus cusp forms.
The quadratic forms used in Theta Tracing are listed at the end of this web page.
We computed Tr(ϑPϑQ) for all 171 combinations of P,Q∈A4.
We truncated the Fourier series to the first 756 coefficients (which corresponded to going up to determinant 431/4),
and the rank of these truncated series was computed mod 19 to be 119,
and this proved dim S4(K(547))- ≥ 119.

The two inequalities on the plus and minus subspaces suffice to prove the wt 4 dimensions as claimed because we know a priori that dim S4(K(547)) = 597.


PROVING UPPER BOUND ON NUMBER OF WEIGHT 2 NONLIFTS
We claim:
     At most number of wt 2 plus nonlifts: 0
     At most number of wt 2 minus nonlifts: 0
Using the spanning set above for S4(K(547))+, we could only compute that
     dim H(2)''+ ≤ 10
which did not imply anything about the nonexistence of nonlifts. Instead, we computed H(2)'+ which had dimension at most 142 and we used the "g1, g2" method by taking
     g1 = G1
     g2 = G4
and showed that there were no nonzero solutions to h2*g1=h1*g2 for h1,h2 ∈ H(2)'+. This proves that there are no plus wt 2 nonlifts.
Using the spanning set above for S4(K(547))-, we could only compute that
     dim H(2)- ≤ 21
which did not imply anything about the nonexistence of nonlifts. We used the "g1, g2" method by taking
     g1 = G1+G20
     g2 = G2+G3+G4
and showed that there were no nonzero solutions to h2*g1=h1*g2 for h1,h2 ∈ H(2)-. This proves that there are no minus wt 2 nonlifts.


Dimensions of subspaces of S4(K(547))+ as we Hecke smear.
Just for curiosity, here is a table that shows how the dimensions of the subspaces progress as we increase the number of Hecke smears. Denote W=span of the products of wt 2 Gritsenko lifts.
Subspace of S4(K(547))+ dimension
W209
Above along with T2(W)418
Above along with T3(W)475
Above along with T4(W)477
Above along with T5(W)478


Weight 2 Theta Blocks
     G1 = Grit(THBK2(4,4,4,5,8,9,11,13,15,19))
     G2 = Grit(THBK2(3,4,5,7,7,8,11,12,16,19))
     G3 = Grit(THBK2(3,4,5,6,9,9,10,11,15,20))
     G4 = Grit(THBK2(3,4,5,6,6,9,9,12,15,21))
     G5 = Grit(THBK2(3,4,5,5,8,9,11,14,14,19))
     G6 = Grit(THBK2(3,4,4,6,7,9,10,11,15,21))
     G7 = Grit(THBK2(3,3,5,8,8,8,11,11,16,19))
     G8 = Grit(THBK2(3,3,4,7,7,10,11,14,16,17))
     G9 = Grit(THBK2(3,3,4,6,7,8,9,11,15,22))
     G10 = Grit(THBK2(3,3,4,5,8,9,11,12,15,20))
     G11 = Grit(THBK2(3,3,4,5,8,8,11,13,16,19))
     G12 = Grit(THBK2(2,4,6,7,8,8,10,12,16,19))
     G13 = Grit(THBK2(2,4,6,7,7,9,11,13,13,20))
     G14 = Grit(THBK2(2,4,6,7,7,8,11,13,15,19))
     G15 = Grit(THBK2(2,4,6,6,8,9,10,12,17,18))
     G16 = Grit(THBK2(2,4,5,7,9,9,10,11,16,19))
     G17 = Grit(THBK2(2,4,5,6,8,9,11,13,17,17))
     G18 = Grit(THBK2(2,4,5,6,7,8,10,12,16,20))
     G19 = Grit(THBK2(2,3,5,7,8,9,11,14,16,17))
     G20 = Grit(THBK2(2,3,5,6,8,8,11,11,17,19))


The set A4 of 4x4 matrices used in theta tracing. Here |A4|=18.
     {{16,1,-3,3},{1,18,3,6},{-3,3,24,10},{3,6,10,52}}
     {{16,1,-3,4},{1,18,3,5},{-3,3,24,2},{4,5,2,48}}
     {{16,1,-1,7},{1,24,10,11},{-1,10,30,14},{7,11,14,42}}
     {{16,1,4,5},{1,20,4,2},{4,4,36,17},{5,2,17,36}}
     {{16,4,5,6},{4,22,10,9},{5,10,28,5},{6,9,5,44}}
     {{16,5,3,-5},{5,22,10,-4},{3,10,28,3},{-5,-4,3,42}}
     {{18,3,0,5},{3,24,8,10},{0,8,26,7},{5,10,7,36}}
     {{18,3,5,7},{3,26,4,10},{5,4,28,9},{7,10,9,32}}
     {{18,5,7,7},{5,28,10,9},{7,10,28,6},{7,9,6,32}}
     {{18,6,6,7},{6,24,7,4},{6,7,28,11},{7,4,11,36}}
     {{20,1,-2,-7},{1,26,13,-8},{-2,13,30,0},{-7,-8,0,30}}
     {{20,1,2,-6},{1,24,11,7},{2,11,28,13},{-6,7,13,36}}
     {{20,4,3,7},{4,24,6,11},{3,6,30,8},{7,11,8,30}}
     {{20,5,2,7},{5,22,8,10},{2,8,24,5},{7,10,5,40}}
     {{20,5,4,6},{5,24,10,5},{4,10,26,11},{6,5,11,36}}
     {{20,9,6,7},{9,26,8,10},{6,8,28,5},{7,10,5,32}}
     {{22,3,7,-6},{3,24,5,10},{7,5,24,1},{-6,10,1,34}}
     {{22,3,7,0},{3,24,5,3},{7,5,24,10},{0,3,10,32}}