We consider the problem of generating a lattice-free convex set to find a valid inequality that minimizes the sum of its coefficients for 2-row simplex cuts. Multi-row simplex cuts has been receiving considerable attention recently and we show that a pseudo-polytime generation of a lattice-free convex set is possible. We conclude with a short numerical study.

We describe an algorithm to learn word pronunciations from acoustic data. The algorithm jointly optimizes the pronunciation of a word using (a) the acoustic match of this pronunciation to the observed data, and (b) how “linguistically reasonable” the pronunciation is. Variations of word pronunciations in the recognition dictionary (which was created by linguists), are used to train a model of w...

It is common practice in statistical data analysis to perform data-driven variable selection and derive statistical inference from the resulting model. Such inference enjoys none of the guarantees that classical statistical theory provides for tests and confidence intervals when the model has been chosen a priori. We propose to produce valid “post-selection inference” by reducing the problem to...

Information in databases can be imperfect and this imperfection has several forms and causes. In some cases, a single value should be stored, but it is (partially) unknown. The uncertainty about which value to store leads to the aforementioned imperfection. In temporal databases, uncertainty can arise, concerning which temporal notion needs to be stored. Because in temporal databases, temporal ...

Tuples of a temporal relation are equipped with a valid time period. A simple extension of the SPC (SelectionProjection-Cross product) algebra for temporal relations is defined, which conforms to primitives in existing temporal query languages. In particular, temporal projection involves coalescing of time intervals, which results in non-monotonic queries. Also the “select-from-where” normal fo...

Allen Interval Algebra introduces a set of operators, which describe any possible temporal association between two valid time intervals. The requirement of Allen operators for complete temporal knowledge goes against the monotonic knowledge generation sequence, which is witnessed in observation driven fields like stratigraphy. In such cases, incomplete temporal information yields a disjunctive ...

In this paper, we present a spatiotemporal information integrated RDF data management system, called g-Store. In g-Store, some entities have spatiotemporal features, and some statements have valid time intervals and occurring locations. We introduce some spatiotemporal assertions into the SPARQL query language to answer the spatiotemporal range queries and join queries. Some examples are listed...

The databases of a wide range of applications, e.g., in data warehousing, store multiple states of time-evolving data. These databases contain a substantial part of now-relative data: data that became valid at some past time and remains valid until the current time. More specifically, two temporal aspects of data are frequently of interest, namely valid time, when data is true, and transaction ...

Although temporal databases have received considerable at tent ion as a topic for research, little work in the area has paid at tent ion t o the concurrency control mechanisms that might be employed in temporal databases. This paper describes how the not ion of the current time also called ‘now’ i n valid-time databases can cause standard serialisation theory t o give what are a t least unintui...

In bitemporal databases, current facts and transaction states are modelled using a special value to represent the current time (such as a minimum or maximum timestamp or NULL). Previous studies indicate that the choice of value for now (i.e. the current time) significantly influences the efficiency of accessing bitemporal data. This paper introduces a new approach to represent now, in which cur...