Circular splicing systems are a formal model of a generative mechanism of circular words, inspired by a recombinant behaviour of circular DNA. Some unanswered questions are related to the computational power of such systems, and finding a characterization of the class of circular languages generated by circular splicing systems is still an open problem. In this paper we solve this problem for c...

The main focus of this paper is the characterization of generic musical structure in terms of the apparatus of formal language theory. It is argued that musical competence falls into the same class as natural language with respect to strong generative capacity – the class of mildly context-sensitive languages described by Joshi (1985).

In this paper M-grammars tha t are used in the Roset ta t ranslat ion system will be looked at as the specification of a t t r ibu te grammars. We will show tha t the a t t r ibute evaluation order is such tha t instead of the special-purpose parsing and generation algorithms introduced for M-grammars in Appelo et al.(1987), also Earley-like context-free parsing and ordinary generation strategi...

The paper discusses some classes of contextual grammars--mainly those with "maximal use of selectors"--giving some arguments that these grammars can be considered a good model for natural language syntax. A contextual grammar produces a language starting from a finite set of words and iteratively adding contexts to the currently generated words, according to a selection procedure: each context ...

We study languages and formal power series associated to (variants of) the Hammersley process. We show that the ordinary Hammersley process yields a regular language and the Hammersley tree process yields deterministic context-free (but non-regular) languages. For the Hammersley interval process we show that there are two relevant variants of formal languages. One of them leads to the same lang...

The following theorem is proved: a formal language without the empty word is context-free if and only if it is generated by some L(\; p1)-grammar, where L(\; p1) is the Lambek calculus with one division and one primitive type. To do that, we use a substitution of types which reduces derivability in L(\) to derivability in L(\; p1).

We consider the language consisting of all words such that it is possible to obtain the empty word by iteratively deleting powers. It turns out that in the case of deleting squares in binary words this language is regular, and in the case of deleting squares in words over a larger alphabet the language is not regular. However, for deleting squares over any alphabet we find that this language ca...

In most previous works, histograms are simply treated as n-dimensional arrays or even reshaped into vectors when measuring the distances between them. However many histograms have their intrinsic topologies, such as HSV histogram (cone), shape context (polar), orientation histogram (circle). The topologies are important for so-called cross-bin distance, because they determine the similarities b...

We obtain a correct generalization of Shokurov’s nonvanishing theorem for log canonical pairs. It implies the base point free theorem for log canonical pairs. We also prove the rationality theorem for log canonical pairs. As a corollary, we obtain the cone theorem for log canonical pairs. We do not need Ambro’s theory of quasi-log varieties.