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Two-Variable Logic with Two Order Relations

Thomas Schwentick ; Thomas Zeume.

It is shown that the finite satisfiability problem for two-variable logic over structures with one total preorder relation, its induced successor relation, one linear order relation and some further unary relations is EXPSPACE-complete. Actually, EXPSPACE-completeness already holds for structures&nbsp;[&hellip;]

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A note on the expressive power of linear orders

Thomas Schwentick ; Nicole Schweikardt.

This article shows that there exist two particular linear orders such that first-order logic with these two linear orders has the same expressive power as first-order logic with the Bit-predicate FO(Bit). As a corollary we obtain that there also exists a built-in permutation such that first-order&nbsp;[&hellip;]

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Rewriting with Acyclic Queries: Mind Your Head

Gaetano Geck ; Jens Keppeler ; Thomas Schwentick ; Christopher Spinrath.

The paper studies the rewriting problem, that is, the decision problem whether, for a given conjunctive query $Q$ and a set $\mathcal{V}$ of views, there is a conjunctive query $Q'$ over $\mathcal{V}$ that is equivalent to $Q$, for cases where the query, the views, and/or the desired rewriting are&nbsp;[&hellip;]

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