## The behaviour of general theta functions under the modular group and the characters of binary modular congruence groups I, II, Ann. of Math

- Hendrik Douwe Kloosterman
- 1946

@inproceedings{Skoruppa2008ReductionM, title={Reduction Mod ℓ of Theta Series of Level ℓ 1 Statement of Results}, author={Nils-Peter Skoruppa}, year={2008} }

- Published 2008

It is proved that the theta series of an even lattice whose level is a power of a prime l is congruent modulo l to an elliptic modular form of level 1. The proof uses arithmetic and algebraic properties of lattices rather than methods from the theory of modular forms. The methods presented here may therefore be especially pleasing to those working in the theory of quadratic forms, and they admit generalizations to more general types of theta series as they occur e.g. in the theory of Siegel or… CONTINUE READING