A new proof that a mapping is regular if and only if it is almost periodic.

A Negative Conjunctive Query is Easy if and only if it is Beta-Acyclic

It is known that the data complexity of a Conjunctive Query (CQ) is determined only by the way its variables are shared between atoms, reflected by its hypergraph. In particular, Yannakakis [18, 3] proved that a CQ is decidable in linear time when it is α-acyclic, i.e. its hypergraph is α-acyclic; Bagan et al. [2] even state: Any CQ is decidable in linear time iff it is α-acyclic. (under certai...

Semi - aposyndetic continuum X is metrizable if and only if it

The main purpose of this paper is to prove the metrizability of semi-aposyndetic continuum X which admits a Whitney map for C(X).

What is episodic memory if it is a natural kind?

What if feedback only counted if the learner used it?

Most teachers give written feedback because it is a required deliverable, like a checkout assistant handing every customer the printed receipt, even though few use them. However there is no point in giving feedback unless the learner uses it: modifies or actively reappraises something specific as a result. This paper explores the theoretical and practical implications of taking this as the star...

Embedding If and Only If

Compounds of indicative conditionals present some puzzling phenomena. Perhaps most striking, some nested indicative conditionals are uninterpretable. Proponents of NTV hold that indicative conditionals do not have truth values, and they use this to explain why nested indicative conditionals are sometimes uninterpretable: the embedded conditional does not provide the truth conditions needed by t...