• Case Studies in Constructive Mathematics 

      Parmann, Erik (Doctoral thesis, 2016-01-22)
      The common theme in this thesis is the study of constructive provability: in particular we investigate aspects of finite sets and Kan simplicial sets from a constructive perspective. There are numerous definitions of finiteness ...
    • Investigating Streamless Sets 

      Parmann, Erik (Conference object; Peer reviewed, 2015)
      In this paper we look at streamless sets, recently investigated by Coquand and Spiwack. A set is streamless if every stream over that set contain a duplicate. It is an open question in constructive mathematics whether the ...
    • Non-Constructivity in Kan Simplicial Sets 

      Bezem, Marc; Coquand, Thierry; Parmann, Erik (Conference object; Peer reviewed, 2015)
      We give an analysis of the non-constructivity of the following basic result: if X and Y are simplicial sets and Y has the Kan extension property, then Y X also has the Kan extension property. By means of Kripke countermodels ...