НАУЧНО-ТЕХНИЧЕСКИЕ ВЕДОМОСТИ САНКТ-ПЕТЕРБУРГСКОГО ГОСУДАРСТВЕННОГО ПОЛИТЕХНИЧЕСКОГО УНИВЕРСИТЕТА. ИНФОРМАТИКА. ТЕЛЕКОММУНИКАЦИИ. УПРАВЛЕНИЕ
We describe a search optimization technique for implementation of relational programming language miniKanren which makes more queries converge. Specifically, we address the problem of conjunction non-commutativity. Our technique is based on a certain divergence criterion that we use to trigger a dynamic reordering of conjuncts. We present a formal semantics of a miniKanren-like language and prove that our optimization does not compromise already converging programs, thus, being a proper improvement. We also present the prototype implementation of the improved search and demonstrate its application for a number of realistic specifications.
We address the problem of transforming typed functional programs into relational form. In this form, a program can be run in various “directions” with some arguments left free, making it possible to acquire different behaviors from a single specification. We specify the syntax, typing rules and semantics for the source language as well as its relational extension, describe the conversion and prove its correctness both in terms of typing and dynamic semantics. We also discuss the limitations of our approach, present the implementation of the conversion for the subset of OCaml and evaluate it on a number of realistic examples.
Welcome to the 20th Symposium on Principles and Practice of Declarative Programming - PPDP 2018! This year's symposium continues the long tradition of bringing together researchers from the various declarative programming communities, including those working in the logic, constraint, and functional programming paradigms. Our mission is to stimulate research in the use of logical formalisms and methods for specifying, performing, and analysing computations, including mechanisms for mobility, modularity, concurrency, objectorientation, security, verification and static analysis. This edition of PPDP was co-located with the 28th International Symposium on Logic-Based Program Synthesis and Transformation, LOPSTR 2018, and the 26th International Workshop on Functional and Logic Programming, WFLP 2018. The programs of PPDP and LOPSTR were overlapping, and two invited speakers were shared, fostering exchange of ideas between the two communities.
A model for organizing cargo transportation between two node stations connected by a railway line which contains a certain number of intermediate stations is considered. The movement of cargo is in one direction. Such a situation may occur, for example, if one of the node stations is located in a region which produce raw material for manufacturing industry located in another region, and there is another node station. The organization of freight traﬃc is performed by means of a number of technologies. These technologies determine the rules for taking on cargo at the initial node station, the rules of interaction between neighboring stations, as well as the rule of distribution of cargo to the ﬁnal node stations. The process of cargo transportation is followed by the set rule of control. For such a model, one must determine possible modes of cargo transportation and describe their properties. This model is described by a ﬁnite-dimensional system of diﬀerential equations with nonlocal linear restrictions. The class of the solution satisfying nonlocal linear restrictions is extremely narrow. It results in the need for the “correct” extension of solutions of a system of diﬀerential equations to a class of quasi-solutions having the distinctive feature of gaps in a countable number of points. It was possible numerically using the Runge–Kutta method of the fourth order to build these quasi-solutions and determine their rate of growth. Let us note that in the technical plan the main complexity consisted in obtaining quasi-solutions satisfying the nonlocal linear restrictions. Furthermore, we investigated the dependence of quasi-solutions and, in particular, sizes of gaps (jumps) of solutions on a number of parameters of the model characterizing a rule of control, technologies for transportation of cargo and intensity of giving of cargo on a node station.
Event logs collected by modern information and technical systems usually contain enough data for automated process models discovery. A variety of algorithms was developed for process models discovery, conformance checking, log to model alignment, comparison of process models, etc., nevertheless a quick analysis of ad-hoc selected parts of a journal still have not get a full-fledged implementation. This paper describes an ROLAP-based method of multidimensional event logs storage for process mining. The result of the analysis of the journal is visualized as directed graph representing the union of all possible event sequences, ranked by their occurrence probability. Our implementation allows the analyst to discover process models for sublogs defined by ad-hoc selection of criteria and value of occurrence probability
The geographic information system (GIS) is based on the first and only Russian Imperial Census of 1897 and the First All-Union Census of the Soviet Union of 1926. The GIS features vector data (shapefiles) of allprovinces of the two states. For the 1897 census, there is information about linguistic, religious, and social estate groups. The part based on the 1926 census features nationality. Both shapefiles include information on gender, rural and urban population. The GIS allows for producing any necessary maps for individual studies of the period which require the administrative boundaries and demographic information.
Existing approaches suggest that IT strategy should be a reflection of business strategy. However, actually organisations do not often follow business strategy even if it is formally declared. In these conditions, IT strategy can be viewed not as a plan, but as an organisational shared view on the role of information systems. This approach generally reflects only a top-down perspective of IT strategy. So, it can be supplemented by a strategic behaviour pattern (i.e., more or less standard response to a changes that is formed as result of previous experience) to implement bottom-up approach. Two components that can help to establish effective reaction regarding new initiatives in IT are proposed here: model of IT-related decision making, and efficiency measurement metric to estimate maturity of business processes and appropriate IT. Usage of proposed tools is demonstrated in practical cases.