Product representation for default bilattices: an application of natural duality theory

• L.M. Cabrer ^[1] ; A.P.K. Craig ^[2] ; H.A. Priestley ^[3]
  1. [1] University of Florence

     University of Florence

     Firenze, Italia

     
  2. [2] University of Johannesburg

     University of Johannesburg

     City of Johannesburg, Sudáfrica

     
  3. [3] University of Oxford

     University of Oxford

     Oxford District, Reino Unido

     

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• Localización: Journal of pure and applied algebra, ISSN 0022-4049, Vol. 219, Nº 7 (July 2015), 2015, págs. 2962-2988
• Idioma: inglés
• DOI: 10.1016/j.jpaa.2014.09.034
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• Resumen

  • Bilattices (that is, sets with two lattice structures) provide an algebraic tool to model simultaneously the validity of, and knowledge about, sentences in an appropriate language. In particular, certain bilattices have been used to model situations in which information is prioritised and so can be viewed hierarchically. These default bilattices are not interlaced: the lattice operations of one lattice structure do not preserve the order of the other one. The well-known product representation theorem for interlaced bilattices does not extend to bilattices which fail to be interlaced and the lack of a product representation has been a handicap to understanding the structure of default bilattices. In this paper we study, from an algebraic perspective, a hierarchy of varieties of default bilattices, allowing for different levels of default. We develop natural dualities for these varieties and thereby obtain a concrete representation for the algebras in each variety. This leads on to a form of product representation that generalises the product representation as this applies to distributive bilattices.