4 papers
A Categorical Approach to Coalgebraic Fixpoint Logic
Ezra Schoen, Clemens Kupke, Jurriaan Rot +1
We define a framework for incorporating alternation-free fixpoint logics into the dual-adjunction setup for coalgebraic modal logics. We achieve this by using order-enriched catego…
Relative fixed points of functors
Ezra Schoen, Jade Master, Clemens Kupke
We show how the relatively initial or relatively terminal fixed points for a well-behaved functor form a pair of adjoint functors between -coalgebras and -algebras. We us…
Lax Liftings and Lax Distributive Laws
Ezra Schoen
Liftings of endofunctors on sets to endofunctors on relations are commonly used to capture bisimulation of coalgebras. Lax versions have been used in those cases where strict lifti…
Beyond Initial Algebras and Final Coalgebras
Ezra Schoen, Jade Master, Clemens Kupke
We provide a construction of the fixed points of functors which may not be inital algebras or final coalgebras. For an endofunctor F, this fixed point construction may be expressed…