An improvement on a theorem of Ben Martin

Amnon Neeman*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Let π be the fundamental group of a Riemann surface of genus g ≥ 2. The group π has a well-known presentation, as the quotient of a free group on generators {a1, a2, . . . , ag, b1, b2, . . . , bg} by the one relation [a1, b1][a2, b2] ⋯ [ag, bg] = 1. This gives two inclusions F π, where F is the free group on g generators; we could map the generators to the a's, or to the b's. Call the images of these inclusions F1 ⊂ π and F2 ⊂ π. Given a connected, reductive group G over an algebraically closed field of characteristic 0, any representation π → G restricts to two representations f1 : F1 → G, f2 : F2 → G. We prove that on a Zariski open, dense subset of the space of pairs of representations {f1, f2}, there exists a representation f : π → G lifting them, up to (separate) conjugacy of f1 and f2. Ben Martin proved this theorem, with the hypothesis that the semisimple rank of G is > g. We remove the hypothesis.

    Original languageEnglish
    Pages (from-to)411-415
    Number of pages5
    JournalMathematical Research Letters
    Volume7
    Issue number4
    DOIs
    Publication statusPublished - 2000

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