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Coalgebra extensions and algebra coextensions of galois type |
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| Authors: | Tomasz Brzeziński Piotr M Hajac |
| Institution: | 1. Department of Mathematics , University of York , Heslington, York, YOl 5DD, U.K E-mail: TB10@YORK.AC.UK;2. International School for Advanced Studies , Via Beirut 2-4, Trieste, 34013, Italy E-mail: HAHAC@SISSA.IT |
| Abstract: | The notion of a coalgebra-Galois extension is defined as a natural generalisation of a Hopf-Galois extension. It is shown that any coalgebra-Galois extension induces a unique entwining map ψ compatible with the right coaction. For the dual notion of an algebra-Galois coextension it is also proven that there always exists a unique entwining structure compatible with the right action. |
| Keywords: | Valuation ring Bounded module type Completion |