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The paper presents a botnet detection approach for the distributed systems. It is based on the developed three level model, which includes botnet’s components: command and control center, control centers, basic elements of the botnet (bots). The novel framework provides the ability to detect known and unknown botnets, and consists of the host and the network levels. At the host level, the detection procedure is based on the implementation of the Bayes classification. The network level extends the results obtained at the host level to the rest of the local area network. Proposed approach provides the exchange of the results obtained by the Bayes classification for further use by other program units of the distributed system. The results of the developed classifier show that representation of the botnets’ samples for different classes and subclasses is sufficient for efficient botnet detection. Proposed technique demonstrates promising results concerning botnet detection in the distributed systems.

The Ternopil Educational Communication Center was developed with NATO funding to improve computing for the universities of Ternopil, Ukraine. It provides high speed access for all of Ternopil’s universities to the Internet and the World Wide Web. It enables high speed communication within Ternopil, and between institutions in Ternopil using the UarNet and URAN networks. It provides an integration of on-line library services, and it supports such activities as video conferencing, distance education, and class to class participation. The universities of Ternopil and the University of Maine are developing programs and projects to involve students and faculty both in Ukraine and the US.

This paper describes the Smart Vehicle Screening System, which can be installed into a tollbooth for automated recognition of vehicle license plate information using a photograph of a vehicle. An automated system could then be implemented to control the payment of fees, parking areas, highways, bridges or tunnels, etc. There are considered an approach to identify vehicle through recognizing of it license plate using image fusion, neural networks and threshold techniques as well as some experimental results to recognize the license plate successfully.

In this paper we examine the history of using random numbers in computer programs. Unfortunately, this history is sad because it is replete with disasters ranging from one of the first pseudo-random number generators, RANDU, beingverybadtothemostrecenteffortsbytheNSAtounderminethepseudorandom number generator in RSA’s BSAFE cryptographic library. Failures in this area have been both intentional and unintentional, but unfortunately the same sorts of mistakes are repeated. The repeated failures in getting our “randomnumbers”correctsuggeststhattheremightbesomesystemicreasons forthesefailures.Inthispaperwereviewsomeofthesefailuresinmoredetail, and the 2006 Debian OpenSSL Debacle in great detail. This last event left users of Debian and its derivatives with seriously compromised cryptographic capabilities for two years. We also illustrate how this failure can be exploited in an attack. We also modify the concept of a system accident developed in the work of Charles Perrow [1]. We identify some system failures in building pseudo-randomnumbergeneratorsandoffersomesuggestionstohelpdevelop PRNGs and other code more securely.

This article gives some background information on the authors’ forthcoming book, The State of Learning. There are many challenges facing educators who want to bring education into the 21st century. At the same time, the explosion of technology has the potential to make education more available and influential than ever before. Education is taking place on a large stage and is not just confined to schools. We must rethink the foundations of education so it can truly benefit from new technology.

Authors suggested the development of a specialized network interface for network of detectors that are part of alarm system. Providing a high level of network security against intruder is achieved using a large number of security elements and their dynamic change in on-line mode network operation. The proposed system uses traditional detectors; each is connected to the network through node based on a microcontroller. This allows connection of traditional detectors into two-wired network with common bus type and to reduce the number of wired lines without loss of system informative channels. An additional advantage is in powering sensors by a server via informational network channel.

We describe the recent developments of an open-source project called RATCHET that can be used by groups of users to collectively construct attack trees. We present the RATCHET framework as well as a model for testing and evaluation of the produced attack trees. RATCHET has been tested in classroom settings with positive results and this paper presents the plans for expanding its outreach to the community at large and building attack trees through crowdsourcing. This paper gives an overview of RATCHET and an introduction to its use.

Bacteria are susceptible to phage (viral) infections. One of the most important properties of phages is host specificity. Phages can be so selective that they will distinguish varieties among apparently identical organisms. By exposing an isolate growing on the surface of an agar plate to a battery of different phages a pattern develops contingent on the susceptibility or resistance of the culture to the phages. A culture sensitive to a particular phage is destroyed and the destruction is manifested by areas devoid of bacterial growth. Using phages to differentiate bacteria is referred to as phage typing. Phage typing can be extremely important in many health situations because it can identify random, unrelated organisms as well as the isolates that are actually responsible for a given problem. Aside from relating an organism to an outbreak, this laboratory method can also be used for surveillance, assessing strain distribution, and ascertaining the effectiveness of therapeutic measures. Phage typing requires the use of a standard collection of dissimilar phages. In the process of developing a phage typing set, numerous phages are first isolated and tests are undertaken to determine if they are different and useful in delineating the types of organisms under study. To make the procedure more cost effective and less labor-intensive the final set is reduced to a manageable number with the assistance of a computer. Selecting a smallest phage typing set is an NP-hard combinatorial search problem so no efficient algorithm for finding it is believed to exist. However, with a powerful computer very good solutions and sometimes optimal solutions can be found by intelligent searching. Using a variety of heuristic techniques and a variety of computers small phage sets have been found previously for Salmonella, Escherichia coli, and Staphylococcus epidermidis. These programs have been rewritten to take advantage of the greater speed and address space of the IBM 3090. We are now able to obtain better results because searching can be done more exhaustively and are able to find optimal phage typing sets, something that we were not able to do with earlier programs running on less powerful computers. We are currently working on a phage typing set for Staphylococcus aureus. Besides finding optimal solutions we also tested a greedy algorithm. Our results suggest that the greedy algorithm works well and should enable us to solve very large problems using powerful computers.

(1992). Misconceptions about the Golden Ratio. The College Mathematics Journal: Vol. 23, No. 1, pp. 2-19.

This paper describes hardware implementations of crypto protocol elements for secured data communication in two wired networks of security system detectors. Those elements are basic to crypto protocol development for that type of network. In addition, hardware tools for the network controller and the network server that support this protocol were developed. These tools will allow us to test and debug the proposed security elements and the crypto protocol.

This paper focuses on the problem of bounding fault detection probabilities in combinational circuits. Two algorithms, the complete cutting algorithm and the gate blocking algorithm, are presented that always produce true lower bounds on the detection probability of a fault. Both algorithms can be used to identify difficult-to-test faults and to quickly construct test sets for specific faults. Both algorithms have qualitative versions which provide insight into a circuit while avoiding arithmetic calculation. Both algorithms resulted from research in trying to determine the accuracy of the safety factor heuristic of Jacob Savir.

Given an undirected distance graph G=(V, E, d) and a set S, where V is the set of vertices in G, E is the set of edges in G, d is a distance function which maps E into the set of nonnegative numbers and S?V is a subset of the vertices of V, the Steiner tree problem is to find a tree of G that spans S with minimal total distance on its edges. In this paper, we analyze a heuristic algorithm for the Steiner tree problem. The heuristic algorithm has a worst case time complexity of O(¦S¦¦V¦ 2) on a random access computer and it guarantees to output a tree that spans S with total distance on its edges no more than 2(1?1/l) times that of the optimal tree, where l is the number of leaves in the optimal tree.

The class of lattices we are interested in (subprojective lattices), can be gotten by taking the MacNeille completions of the class of complemented, modular, atomic lattices. McLaughlin showed that subprojective lattices can be represented as the lattices of W-closed subspaces of a vector space U in duality with a vector space W. In this paper, we give a characterization of subprojective lattices in terms of atoms and dual atoms, by means of an incidence space satisfying self-dual axioms. In the finite-dimensional case, a subprojective lattice is projective, and hence our self-dual axioms characterize finite-dimensional projective spaces in terms of points and hyperplanes. No numerical parameters appear explicitly in these axioms. For each subprojective lattice L with at least three elements, we define a projective envelope P (L) for it. P (L) is a projective lattice and there is a natural inf-preserving injection of L into P (L). This injection has other important properties which we take as the definition of a geometric map. In the course of studying geometric maps, we obtain a lattice theoretic proof of Mackey's result that the join of a U-closed subspace of V and a finite-dimensional subspace is U-closed, where (U, V) form a dual pair of vector spaces over a division ring. Furthermore, we show that if L is a subprojective lattice, P a projective lattice, and ψ: L → P a geometric map, then P is isomorphic to the projective envelope P (L) of L. The paper presents many other properties of subprojective lattices. It concludes with a characterization of subprojective lattices which are also projective.

For a complete lattice L L , in which every element is a join of completely join-irreducibles and a meet of completely meet-irreducibles (we say L L is a jm-lattice) we define the poset of irreducibles P ( L ) P(L) to be the poset (of height one) J ( L ) ∪ M ( L ) ( J ( L ) J(L) \cup M(L)(J(L) is the set of completely join-irreducibles and M ( L ) M(L) is the set of completely meet-irreducibles) ordered as follows: a > P ( L ) b a{ > _{P(L)}}b if and only if a ∈ J ( L ) , b ∈ M ( L ) a \in J(L),b \in M(L) , and a ⪇ L b a \nleqslant { _L}b . For a jm-lattice L L , the automorphism groups of L L and P ( L ) P(L) are isomorphic, L L can be reconstructed from P ( L ) P(L) , and the irreducible factorization of L L can be gotten from the components of P ( L ) P(L) . In fact, we can give a simple characterization of the center of a jm-lattice in terms of its separators (or unions of connected components of P ( L ) P(L) ). Thus P ( L ) P(L) extends many of the properties of the poset of join-irreducibles of a finite distributive lattice to the class of all jm-lattices. We characterize those posets of height 1 which are P ( L ) P(L) for some jm-lattice L L . We also characterize those posets of height 1 which are P ( L ) P(L) for a completely distributive jm-lattice, as well as those posets which are P ( L ) P(L) for some geometric lattice L L . More generally, if L L is a complete lattice, many of the above arguments apply if we use “join-spanning” and “meet-spanning” subsets of L L , instead of J ( L ) J(L) and M ( L ) M(L) . If L L is an arbitrary lattice, the same arguments apply to “join-generating” and “meet-generating” subsets of L L .

It is shown that ψ ( n ) \psi (n) , the size of the free distributive lattice on n generators (which is the number of isotone Boolean functions on subsets of an n element set), satisfies \[ ψ ( n ) ⩽ 2 ( 1 + O ( log n / n ) ) ( n [ n / 2 ] ) . \psi (n) \leqslant {2^{(1 + O(\log \;n/n))\left ( {\begin {array}{*{20}{c}} n \\ {[n/2]} \\ \end {array} } \right )}}. \] This result is an improvement by a factor n \sqrt n in the 0 term of a previous result of Kleitman. In the course of deriving the main result, we analyze thoroughly the techniques used here and earlier by Kleitman, and show that the result in this paper is “best possible” (up to constant) using these techniques.

Given a sequence of positive weights, W=w 1?...?w n >0, there is a Huffman tree, T? ("T-up") which minimizes the following functions: max{d(wi)}; Σd(wi); Σf(d(wi)) w i(here d(w i) represents the distance of a leaf of weight w i to the root and f is a function defined for nonnegative integers having the property that g(x) = f(x + 1) ? f(x) is monotone increasing) over the set of all trees for W having minimal expected length. Minimizing the first two functions was first done by Schwartz [5]. In the case of codes where W is a sequence of probabilities, this implies that the codes based on T? have all their absolute central moments minimal. In particular, they are the least variance codes which were also described by Kou [3]. Furthermore, there exists a Huffman tree T?, ("T-down") which maximizes the functions considered above. However, if g(x) is monotone decreasing, T? and T?, respectively maximize and minimize Σf(d(wi) w i) over the set of all trees for W having minimal expected length. In addition, we derive a number of interesting results about the distribution of labels within Huffman trees. By suitable modifications of the usual Huffman tree construction, (see [1]) T? and T? can also be constructed in time O(n log n).

In an earlier paper, the authors presented an algorithm for finding all polyhedral solid objects with a given set of vertices and straight line edges (its wire frame). This paper extends the Wire Frame algorithm to find all solid polyhedral objects with a given set of two dimensional projections. These projections may contain depth information in the form of dashed and solid lines, may represent cross sections, and may be overall or detail views. The choice of labeling conventions in the projections determines the difficulty of the problem. It is shown that with certain conventions and projections the problem of fleshing out projections essentially reduces to the problem of fleshing out wire frames. Even if no labeling is used, the Projections algorithm presented here finds all solutions even though it is possible to construct simple examples with a very large number of solutions. Such examples have a large amount of symmetry and various accidental coincidences which typically do not occur in objects of practical interest. Because of its generality, the algorithm can handle pathological cases if they arise. This Projections algorithm, which has applications in the conversion of engineering drawings in a Computer Aided Design, Computer Aided Manufacturing (CADCAM) system, has been implemented. The algorithm has successfully found solutions to problems that are rather complex in terms of either the number of possible solutions or the inherent complexity of projections of objects of engineering interest.

Majority-logic decoding is attractive for three reasons: (1) It can be simply implemented; (2) the decoding delay is short; and (3) its performance, while suboptimal, is always superior to bounded distance decoding. For these reasons, majority-logic decodable cyclic codes are very suitable for error control in high speed digital data transmission systems. Among the majority-logic decodable codes, the one-step decodable codes can be most easily implemented; they employ a single majority-logic gate. In this paper we study a class of one-step majority-logic decodable cyclic codes. First, we describe these codes in a simple manner. Second, a way of finding the orthogonal polynomials for decoding these codes is presented. Third, we show that for a given error correction capability, the ratio of the number of parity digits to the code length goes to zero as the code length increases. For error correction Capabilities of the form 2k - 1 or 2k, we determine the dimensions of the codes exactly.

Given a polyhedral object, its wire frame is the set of its edges and vertices. In this paper we present an algorithm which discovers all objects with a given wire frame. This algorithm, which has a number of applications to mechanical design besides being of mathematical interest, has been implemented and has performed well on complex objects.

A comparative study is made of algorithms for a general multidimensional problem involving the packing of k-part objects in k compartments in a large supply of bins. The goal is to pack the objects using a minimum number of bins. The properties and limitations of the algorithms are discussed, including k-dimensional analogs of some popular one-dimensional algorithms. An application of the algorithms is the design of computer networks.

In two recent papers the authors introduced some new approaches to the problem of modeling the phenomena underlying immunological reaction tests. These approaches allow one to easily construct the best possible models for a given amount of immunological test data. In the first paper the authors used a purely Boolean approach, i.e., it was assumed that the experimenter signified whether or not a reaction occurred in a given test. In the second paper the authors assumed that the relative strengths of the reactions were available as data for the modeling process. They showed that in this case strictly better models could be constructed. This paper generalizes the approaches taken in the first two papers and provides a unified approach to this whole subject. Many of the results, e.g., the ability to construct the best model, of the first two papers hold in this more general setting. Moreover, this generalization allows one to assess the tradeoffs involved in using data on the relative strengths of reactions. In particular, we see that using relative strengths is equivalent to using an additional intersection factor in a strictly Boolean approach. This intersection factor it turns out, can be obtained experimentally by using elution in addition to the absorption involved in the first two papers. Finally, the duality between fragments and cofragments becomes apparent using this approach.

K. A. Zaretskii has associated a lattice V(α) with each binary relation α, and he has shown that Hα is isomorphic with the group of all automorphisms of V(α) if Hα is a group. This result is extended in this paper by showing that for any binary relation α, the Schutzenberger group Γ (Hα) is isomorphic with the group of all automorphisms of V(α).

It is shown that any Boolean expression in disjunctive normal form having k conjuncts, can have at most 2k prime implicants. However, there exist such expressions that have 2k2 prime implicants. It is also shown that any Boolean expression on n distinct propositional variables can have at most O(3nn) prime implicants, and that there exist expressions with ω(3nn prime implicants.

A strong node sequence for a directed graph G=(N,A) is a sequence of nodes containing every cycle-free path of G as a subsequence. A weak node sequence for G is a sequence of nodes containing every basic path in G as a subsequence, where a basic path n 1 , n 2 , …, n k is a path from n 1 to n k such that no proper subsequence is a path from n 1 to n k . (Every strong node sequence for G is a weak node sequence for G. ) Kennedy has developed a global program data flow analysis method using node sequences. Kwiatowski and Kleitman have shown that any strong node sequence for the complete graph on n nodes must have length at least n 2 −O( n 7/4+α ), for arbitrary positive e. Every graph on n nodes has a strong sequence of length n 2 –2n +4, so this bound is tight to within O( n 7/4+α ). However, the complete graph on n nodes has a weak node sequence of length n nodes (all with in-degree and out-degree bounded by two) such that any weak node sequence for G has length at least 1/2 log 2 n −O( n log log n ). Aho and Ullman have shown that every reducible flow graph has a strong node sequence of length O( n log 2 n ); thus our bound is tight to within a constant factor for reducible graphs. We also show that for infinitely many n , there is a (non-reducible) flow graph H with n nodes (all with in-degree and out-degree bounded by two), such that any weak node sequence for H has length at least cn 2 , where c is a positive constant. This bound, too, is tight to within a constant factor.

Given a set, S, of Boolean n-vectors, one can choose k of the n coordinate positions and consider the set of k-vectors which results by keeping only the designated k positions of each vector, i.e., from k-projecting S. In this paper, we study the question of finding sets S as small as possible such that every k-projection of S yields all the 2 k possible k-vectors. We solve this problem constructively and almost optimally for k=2 and all n. For k?3, the constructive solutions we describe are much larger than an O(k 2 k log n) nonconstructive upper bound which we derive. The nonconstructive approach allows us to generate fairly small sets S which have a very high probability of having the surjective k-projection property.

A set composed of 27 phages is described for differentiating Salmonella spp. representative of groups A, B, C1, C2, D1, D2, E1, E2, E3, E4, G1, K, and N. All of the 1,245 cultures used in this effort were typable and were differentiated on the basis of the 420 phage patterns observed. All results were reproducible. Characteristic phage patterns were produced by a variety of Salmonella serovars isolated from campus incidents and a number of hospital, family, restaurant, and processing plant outbreaks to indicate an existing epidemiological relationship.

A phage typing set composed of 32 phages is described for differentiating Escherichia coli. Eight hundred sixty-six isolates from cases of bovine mastitis were used in this effort. Of these cultures 829, or 96%, were characterized successfully, and 178 phage types were observed. Thirty-seven isolates were not typable.

The question of how to learn rules, when those rules make probabilistic statements about the future, is considered. Issues are discussed that arise when attempting to determine what a good prediction function is, when those prediction functions make probabilistic assumptions. Learning has at least two purposes: to enable the learner to make predictions in the future and to satisfy intellectual curiosity as to the underlying cause of a process. Two results related to these distinct goals are given. In both cases, the inputs are a countable collection of functions which make probabilistic statements about a sequence of events. One of the results shows how to find one of the functions, which generated the sequence, the other result allows to do as well in terms of predicting events as the best of the collection. In both cases the results are obtained by evaluating a function based on a tradeoff between its simplicity and the accuracy of its predictions. >

We show that the usual construction of the free distributive lattice on n generators generalizes to an arbitrary quantity of generators and actually yields a free completely distributive lattice. Furthermore, for an infinite number of generators the cardinality of the corresponding free completely distributive lattice is exactly that of the power set of the power set of the set of generators.