arXiv subjects

Oleg Kiselyov

Publications and source records attributed to Oleg Kiselyov.

24 records · Page 2Linked to original sources

arXiv2003

Subclassing errors, OOP, and practically checkable rules to prevent them

This paper considers an example of Object-Oriented Programming (OOP) leading to subtle errors that break separation of interface and implementations. A comprehensive principle that guards against such errors is undecidable. The paper introduces a set of mechanically verifiable rules that prevent these insidious problems. Although the rules seem restrictive, they are powerful and expressive, as we show on several familiar examples. The rules contradict both the spirit and the letter of the OOP. The present examples as well as available theoretical and experimental results pose a question if OOP is conducive to software development at all.

cs.PL↗

arXiv2001

Secure Counting: counting members of a subset without revealing their identities

Suppose there is a group of N people some of whom possess a specific property. For example, their wealth is above or below a threshold, they voted for a particular candidate, they have a certain disease, etc. The group wants to find out how many of its members posses the property -- without revealing the identities. Unless of course it turns out that all members do or do not have the attribute of interest. However, in all other cases the counting algorithm should guarantee that nobody can find out if a particular individual possesses the property unless all the other N-1 members of the group collude. The present article describes a method to solve the confidential counting problem with only 3*N-2 pairwise communications, or 2*N broadcasts (the last N-1 pairwise communications are merely to announce the result). The counting algorithm does not require any trusted third parties. All communications between parties involved can be conducted in public without compromising the security of counting.

cs.CR↗

arXiv2001

Type Arithmetics: Computation based on the theory of types

The present paper shows meta-programming turn programming, which is rich enough to express arbitrary arithmetic computations. We demonstrate a type system that implements Peano arithmetics, slightly generalized to negative numbers. Certain types in this system denote numerals. Arithmetic operations on such types-numerals - addition, subtraction, and even division - are expressed as type reduction rules executed by a compiler. A remarkable trait is that division by zero becomes a type error - and reported as such by a compiler.

cs.CL↗

arXiv2000

A network file system over HTTP: remote access and modification of files and "files"

The goal of the present HTTPFS project is to enable access to remote files, directories, and other containers through an HTTP pipe. HTTPFS system permits retrieval, creation and modification of these resources as if they were regular files and directories on a local filesystem. The remote host can be any UNIX or Win9x/WinNT box that is capable of running a Perl CGI script and accessible either directly or via a web proxy or a gateway. HTTPFS runs entirely in user space. The current implementation fully supports reading as well as creating, writing, appending, and truncating of files on a remote HTTP host. HTTPFS provides an isolation level for concurrent file access stronger than the one mandated by POSIX file system semantics, closer to that of AFS. Both an API with familiar open(), read(), write(), close(), etc. calls, and an interactive interface, via the popular Midnight Commander file browser, are provided.

cs.OS↗

arXiv2000

Image Compression with Iterated Function Systems, Finite Automata and Zerotrees: Grand Unification

Fractal image compression, Culik's image compression and zerotree prediction coding of wavelet image decomposition coefficients succeed only because typical images being compressed possess a significant degree of self-similarity. Besides the common concept, these methods turn out to be even more tightly related, to the point of algorithmical reducibility of one technique to another. The goal of the present paper is to demonstrate these relations. The paper offers a plain-term interpretation of Culik's image compression, in regular image processing terms, without resorting to finite state machines and similar lofty language. The interpretation is shown to be algorithmically related to an IFS fractal image compression method: an IFS can be exactly transformed into Culik's image code. Using this transformation, we will prove that in a self-similar (part of an) image any zero wavelet coefficient is the root of a zerotree, or its branch. The paper discusses the zerotree coding of (wavelet/projection) coefficients as a common predictor/corrector, applied vertically through different layers of a multiresolutional decomposition, rather than within the same view. This interpretation leads to an insight into the evolution of image compression techniques: from a causal single-layer prediction, to non-causal same-view predictions (wavelet decomposition among others) and to a causal cross-layer prediction (zero-trees, Culik's method).

cs.CV↗

arXiv2000

Why C++ is not very fit for GUI programming

With no intent of starting a holy war, this paper lists several annoying C++ birthmarks that the author has come across developing GUI class libraries. C++'s view of classes, instances and hierarchies appears tantalizingly close to GUI concepts of controls, widgets, window classes and subwindows. OO models of C++ and of a window system are however different. C++ was designed to be a "static" language with a lexical name scoping, static type checking and hierarchies defined at compile time. Screen objects on the other hand are inherently dynamic; they usually live well beyond the procedure/block that created them; the hierarchy of widgets is defined to a large extent by layout, visibility and event flow. Many GUI fundamentals such as dynamic and geometric hierarchies of windows and controls, broadcasting and percolation of events are not supported directly by C++ syntax or execution semantics (or supported as "exceptions" -- pun intended). Therefore these features have to be emulated in C++ GUI code. This leads to duplication of a graphical toolkit or a window manager functionality, code bloat, engaging in unsafe practices and forgoing of many strong C++ features (like scoping rules and compile-time type checking). This paper enumerates a few major C++/GUI sores and illustrates them on simple examples.

cs.PL↗