4 papers
Extension preservation on dense graph classes
Ioannis Eleftheriadis
Preservation theorems provide a direct correspondence between the syntactic structure of first-order sentences and the closure properties of their respective classes of models. A l…
Universal slices of the category of graphs
Ioannis Eleftheriadis
We characterise the slices of the category of graphs that are algebraically universal in terms of the structure of the slicing graph. In particular, we show that algebraic universa…
Algebraically universal categories of relational structures
Ioannis Eleftheriadis
We consider categories of relational structures that fully embed every category of universal algebras, and prove a partial characterisation of these in terms of an infinitary varia…
Monadic NIP in monotone classes of relational structures
Samuel Braunfeld, Anuj Dawar, Ioannis Eleftheriadis +1
We prove that for any monotone class of finite relational structures, the first-order theory of the class is NIP in the sense of stability theory if, and only if, the collection of…