We compute bounds on covering maps that arise in Belyi's Theorem. In particular, we construct a library of height properties and then apply it to algorithms that produce Belyi maps. Such maps are used to give coverings from algebraic curves to the projective line ramified over at most three points.
Towards an Effective Version of a Theorem of Stafford
β Scribed by Andre Hillebrand; Wiland Schmale
- Publisher
- Elsevier Science
- Year
- 2001
- Tongue
- English
- Weight
- 317 KB
- Volume
- 32
- Category
- Article
- ISSN
- 0747-7171
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β¦ Synopsis
A classical theorem of Stafford says: every left ideal of partial differential operators with rational or even polynomial coefficients in n variables can be generated by two elements. The highly involved proof of this theorem is reorganized and completed for rational coefficients in order to yield a procedure which guarantees the computability in finitely many steps. Consequences for an eventual normal form for matrices of such operators are discussed.
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