JournalsrlmVol. 23, No. 1pp. 69–87

Completeness of Reidemeister-type moves for surfaces embedded in three-dimensional space

  • Giovanni Bellettini

    Università di Roma 'Tor Vergata', Italy
  • Valentina Beorchia

    Università di Trieste, Italy
  • Maurizio Paolini

    Università Cattolica del Sacro Cuore, Brescia, Italy
Completeness of Reidemeister-type moves for surfaces embedded in three-dimensional space cover
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Abstract

In this paper we are concerned with labelled apparent contours, namely with apparent contours of generic orthogonal projections of embedded surfaces in R3\mathbb R^3, endowed with a suitable information on the relative depth. We give a proof of the following theorem: there exists a finite set of elementary moves (i.e. local topological changes) on labelled apparent contours such that two generic embeddings in R3\mathbb R^3 of a closed surface are isotopic if and only if their apparent contours can be connected using only smooth planar isotopies and a finite sequence of moves. This result, that can be obtained as a by-product of general results on knotted surfaces and singularity theory, is obtained here with a direct and rather elementary proof.

Cite this article

Giovanni Bellettini, Valentina Beorchia, Maurizio Paolini, Completeness of Reidemeister-type moves for surfaces embedded in three-dimensional space. Atti Accad. Naz. Lincei Cl. Sci. Fis. Mat. Natur. 23 (2012), no. 1, pp. 69–87

DOI 10.4171/RLM/617