We give a geometric condition that characterizes MELL proof structures whose interpretation is a clique in non-uniform coherent spaces: visible acyclicity. We define the visible paths and we prove that the proof structures which have no visible cycles are exactly those whose interpretation is a clique. It turns out that visible acyclicity has also nice computational properties, especially it is...

It is proved that for a commutative noetherian ring with dualizing complex the homotopy category of projective modules is equivalent, as a triangulated category, to the homotopy category of injective modules. Restricted to compact objects, this statement is a reinterpretation of Grothendieck’s duality theorem. Using this equivalence it is proved that the (Verdier) quotient of the category of ac...

The restricted chase is a sound and complete algorithm for conjunctive query answering over ontologies of disjunctive existential rules. We develop acyclicity conditions to ensure its termination. Our criteria cannot always detect termination (the problem is undecidable), and we develop the first cyclicity criteria to show non-termination of the restricted chase. Experiments on real-world ontol...

We prove that a Tate construction A〈u1, . . . , un | ∂(ui) = zi〉 over a DG algebra A, on cycles z1, . . . , zn in A> 1, is acyclic if and only the map of graded-commutative algebras H0(A)[y1, . . . , yn] → H(A), with yi 7→ cls(zi), is an isomorphism. This is used to establish that if a large homomorphism R → S has an acyclic closure R〈U〉 with sup{i | Ui 6= ∅} = s < ∞, then s is either 1 or an e...

We study situations of allocating positions to students based on priorities. An example is the assignment of medical students to hospital residencies on the basis of entrance exams. For markets without couples, e.g., for undergraduate student placement, acyclicity is a necessary and sufficient condition for the existence of a fair and efficient placement mechanism (Ergin, 2002). We show that in...

Answer set programming (ASP) is a declarative programming paradigm for solving search problems arising in knowledge-intensive domains. One viable way to implement the computation of answer sets corresponding to problem solutions is to recast a logic program as a Boolean satisfiability (SAT) problem and to use existing SAT solver technology for the actual search. Such mappings can be obtained by...

We consider iterative voting models and position them within the general framework of acyclic games and game forms. More specifically, we classify convergence results based on the underlying assumptions on the agent scheduler (the order of players) and the action scheduler (which better-reply is played). Our main technical result is providing a complete picture of conditions for acyclicity in s...

A class of structures satisfies the extension preservation theorem if, on this class, every first order sentence is preserved under extension iff it is equivalent to an existential sentence. We consider different acyclicity notions for hypergraphs (γ, β and α-acyclicity and also acyclicity on hypergraph quotients) and estimate their influence on the validity of the extension preservation theore...

In this paper we review some well-known theory about reduction strategies of various kinds: normalizing, outermost-fair, cofinal, Church-Rosser. A stumbling block in the definition of such strategies is the presence of reduction cycles that may ‘trap’ a strategy as it is memory-free. We exploit a recently (re)discovered fact that there are no reduction cycles in orthogonal rewrite systems when ...