1,720,997 research outputs found
Picture codes and deciphering delay
No full textA set. X of pictures over an alphabet Σ is a code if any picture over Σ is tilable in at most one way with pictures in. X. The codicity problem is in general undecidable. Recently, the prefix picture codes were introduced as a decidable subclass of codes that generalize the prefix string codes. In the string theory, the finite deciphering delay sets are some interesting codes which coincide with the prefix codes when the delay is equal to 0. An analogous notion is introduced for the picture codes and it is proved that the codes with deciphering delay. k form a decidable class of picture codes which includes interesting examples and special cases
Non-expandable non-overlapping sets of pictures
No full textThe non-overlapping sets of pictures are sets such that no two pictures in the set (properly) overlap. They are the generalization to two dimensions of the cross-bifix-free sets of strings. Non-overlapping sets of pictures are non-expandable when no other picture can be added without violating the property. We propose a general construction method for non-expandable non-overlapping (NENO) sets based on some structural properties of NENO sets. As an application, we show a first example of a family of NENO sets
Full sets of pictures to encode pictures
No full textA picture, or two-dimensional (2D) string, is a rectangular array of symbols over a finite alphabet. In this paper, we introduce the notion of fullness for sets of strings and sets of pictures. Fullness is a local counterpart of completeness. While in 1D fullness coincides with completeness, in 2D complete sets of pictures are a subset of full ones. This new notion allows introducing the encoding of a picture. The definition of encoding is based on the one of cutting decomposition. If a set of pictures X is full then any picture has an encoding over X; furthermore, the encoding is unique if X is a univocally full set. Univocally full sets coincide with the maximal strong prefix codes of pictures that were recently introduced. At last, we show an encoding algorithm for pictures, which relies on a new tree data structure to represent univocally full sets
Unbordered pictures: Properties and construction
No full textThe notion of unbordered picture generalizes to two dimensions the notion of unbordered (or bifix-free) string. We extend to two dimensions Nielsen’s construction of unbordered strings ([23]) and describe an algorithm to construct the set U(m, n) of unbordered pictures of fixed size (m, n). The algorithm recursively computes the set of quasi-unbordered pictures Q(m, n), i.e. pictures that can possibly have some “large” borders
Tiling recognizable two-dimensional languages
No full textTiling recognizable two-dimensional languages generalizes recognizable string languages to two dimensions and share with them several properties. Nevertheless two-dimensional recognizable languages are not closed under complement and this implies that are intrinsically non-deterministic. We introduce the notion of deterministic and unambiguous tiling system that generalizes deterministic and unambiguous automata for strings and show that, differently from the one-dimensional case, there exist other distinct classes besides deterministic, unambiguous and non-deterministic families that can be separated by means of examples and decidability-properties. Finally we introduce a model of automaton, referred to as tiling automaton, defined as a scanning strategy plus a transition function given by a tiling system. Languages recognized. by tiling automata are compared with ones recognized by on-line tesselation automata and four-way automata
Encoding pictures with maximal codes of pictures
No full textA picture is a two-dimensional counterpart of a string and it is represented by a rectangular array of symbols over a finite alphabet Σ. A set X of pictures over Σ is a code if every picture over Σ is tilable in at most one way with pictures in X. Recently, the definition of strong prefix code was introduced as a decidable family of picture codes, and a construction procedure for maximal strong prefix (MSP) codes was proposed. Unfortunately, the notion of completeness cannot be directly transposed from strings to pictures without loosing important properties. We generalize to pictures a special property satisfied by complete set of strings that allow to prove interesting characterization results for MSP codes. Moreover, we show an encoding algorithm for pictures using pictures from a MSP code. The algorithm is based on a new data structure for the representation of MSP codes
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
- …
