This paper introduces a class of formal grammars made up by augmenting the formalism of context-free grammars with an explicit set-theoretic intersection operation. It is shown that conjunctive grammars can generate some important non-contextfree language constructs, including those not in the intersection closure of context-free languages, and that they can provide very succinct descriptions o...

Conjunctive grammars were introduced by A. Okhotin in [1] as a natural extension of context-free grammars with an additional operation of intersection in the body of any production of the grammar. Several theorems and algorithms for context-free grammars generalize to the conjunctive case. Still some questions remained open. A. Okhotin posed nine problems concerning those grammars. One of them ...

Economic models and watershed provide useful results, but when seeking to integrate these systems, the temporal units typically utilized by must be reconciled. A hydrologic-economic modeling framework is built couple Hydrological Simulation Program-Fortran (HSPF), representing system, with Rectangular Choice-of-Technology (RCOT) model, an extension of basic input-output (I-O) model. This implem...

We consider the feature-generation task wherein we are given a database with entities labeled as positive and negative examples, want to find feature queries that linearly separate two sets of examples. focus on conjunctive queries, explore problems: (a) deciding if separating exist (separability), (b) generating such when they exist. To restrict complexity generated classifiers, various ways r...