Belyi map
imported>Pythagoras0님의 2014년 4월 28일 (월) 19:17 판
introduction
- Belyi's theorem on algebraic curves
- any non-singular algebraic curve C, defined by algebraic number coefficients, represents a compact Riemann surface which is a ramified covering of the Riemann sphere, ramified at three points $\{0,1,\infty\}$ only.
- Belyi map gives rise to a projective curve
Belyi maps of degree 2
- Belyi map $f:\mathbb{P}^1\to \mathbb{P}^1$ defined by $z\mapsto z^2$
Grobner techniques
- start with three permutations $(12), (23), (132)$. They generate $S_3$.
- Riemann-Hurwitz formula gives the genus $g=1-3+(1+1+2)/2=0$
complex analytic method
- using modular forms
p-adic method
history
expositions
- Sijsling, Jeroen, and John Voight. 2013. “On Computing Belyi Maps.” arXiv:1311.2529 [math] (November 11). http://arxiv.org/abs/1311.2529.
- Zvonkin, Belyi functions: examples, properties, and applications
- Magot, Nicolas, and Alexander Zvonkin. 2000. “Belyi Functions for Archimedean Solids.” Discrete Mathematics 217 (1–3) (April 28): 249–271. doi:10.1016/S0012-365X(99)00266-6.
articles
- Klug, Michael, Michael Musty, Sam Schiavone, and John Voight. 2013. “Numerical Calculation of Three-Point Branched Covers of the Projective Line.” arXiv:1311.2081 [math] (November 8). http://arxiv.org/abs/1311.2081.
- Köck, Bernhard. “Belyi’s Theorem Revisited.” arXiv:math/0108222, August 31, 2001. http://arxiv.org/abs/math/0108222.
encyclopedia