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Rigid local systems and motives of type G2. With an appendix by Michale Dettweiler and Nicholas M. Katz

Published online by Cambridge University Press:  24 March 2010

Michael Dettweiler
Affiliation:
Interdisciplinary Center for Scientific Computing (IWR), University of Heidelberg, 69120 Heidelberg, Germany (email: [email protected])
Stefan Reiter
Affiliation:
Institut für Mathematik, Johannes Gutenberg Universität Mainz, D-55099, Mainz, Germany (email: [email protected])
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Abstract

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Using the middle convolution functor MCχ introduced by N. Katz, we prove the existence of rigid local systems whose monodromy is dense in the simple algebraic group G2. We derive the existence of motives for motivated cycles which have a motivic Galois group of type G2. Granting Grothendieck’s standard conjectures, the existence of motives with motivic Galois group of type G2 can be deduced, giving a partial answer to a question of Serre.

Type
Research Article
Copyright
Copyright © Foundation Compositio Mathematica 2010

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