Breaking and restoring of diffeomorphism symmetry in discrete gravity

Abstract

We discuss the fate of diffeomorphism symmetry in discrete gravity. Diffeomorphism symmetry is typically broken by the discretization. This has repercussions for the observable content and the canonical formulation of the theory. It might however be possible to construct discrete actions, so--called perfect actions, with exact symmetries and we will review first steps towards this end.

to appear in the Proceedings of the XXV Max Born Symposium "The Planck Scale", Wroclaw, 29 June - 3 July, 2009

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• Coarse graining free theories with gauge symmetries: the linearized case
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• Topological lattice field theories from intertwiner dynamics
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