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Moduli spaces of Klein surfaces and related operads
Christopher Braun
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Algebraic & Geometric Topology 12
(2012) 1831–1899
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Abstract
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We consider the extension of classical 2–dimensional topological quantum field
theories to Klein topological quantum field theories which allow unorientable
surfaces. We approach this using the theory of modular operads by introducing a
new operad governing associative algebras with involution. This operad is
Koszul and we identify the dual dg operad governing A∞–algebras with
involution in terms of Möbius graphs which are a generalisation of ribbon
graphs. We then generalise open topological conformal field theories to open
Klein topological conformal field theories and give a generators and relations
description of the open KTCFT operad. We deduce an analogue of the ribbon
graph decomposition of the moduli spaces of Riemann surfaces: a Möbius
graph decomposition of the moduli spaces of Klein surfaces (real algebraic
curves). The Möbius graph complex then computes the homology of these
moduli spaces. We also obtain a different graph complex computing the
homology of the moduli spaces of admissible stable symmetric Riemann
surfaces which are partial compactifications of the moduli spaces of Klein
surfaces.
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Keywords
moduli space, Klein surfaces, mobius
graphs, graph complex, topological quantum field theories,
operads, modular operads
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Mathematical Subject Classification
Primary: 30F50, 32G15
Secondary: 18D50, 57R56, 81T40
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Publication
Received: 30 March 2010
Revised: 25 August 2011
Accepted: 8 May 2012
Published: 7 September 2012
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