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January, 23  Tarmo Uustalu (Institute of Cybernetics, Tallinn)

The concept of recursive coalgebra of a functor was introduced in
the 1970s by Osius in his work on categorical set theory to discuss the
relationship between wellfounded induction and recursive function
definition. In this talk, I will motivate the use of recursive
coalgebras as a paradigm of structured recursion in programming
semantics, list some basic facts about recursive coalgebras and give
new conditions for the recursiveness of a coalgebra based on comonads,
comonadcoalgebras and distributive laws of functors over comonads.
Time
permitting, I will also touch upon related concepts such as Taylor's
wellfounded coalgebras and Adámek, Lücke and Milius's coalgebras with a
map to the initial algebra.
Joint work with Venanzio Capretta, University of Ottawa, Varmo Vene, University of Tartu. 
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