ppxscal/embedding_network huggingface dataset:
Software Tamper Resistance: Obstructing Static Analysis of Programs
Authors: Chenxi Wang, Jonathan Hill, John Knight, Jack Davidson
Venue:  (2000)

Reliable execution of software on untrustworthy platforms is a difficult problem. On the one hand, the underlying system services cannot be relied upon to provide execution assurance, while on the other hand, the effect of a tampered execution can be disastrous -- consider intrusion detection programs. What is needed, in this case, is tamper resistant software. Code obfuscation has been an area of development, in part, to enhance software tamper resistance. However, most obfuscation techniques are ad hoc, without the support of sound theoretical basis or provable results. In this paper, we address one aspect of software protection by obstructing static analysis of programs. Our techniques are based, fundamentally, on the difficulty of resolving aliases in programs. The presence of aliases has been proven to greatly restrict the precision of static data-flow analysis. Meanwhile, effective alias detection has been shown to be NP-Hard. While this represents a significant hurdle for code optimization, it provides a theoretical basis for structuring tamper-resistant programs -- systematic introduction of nontrivial aliases transforms programs to a form that yields data flow information very slowly and/or with little precision. Precise alias analysis relies on the collection of static control flow information. We further hinder the analysis by a systematic "break-down" of the program control-flow; transforming high level control transfers to indirect addressing through aliased pointers. By doing so, we have made the basic control-flow analysis into a general alias analysis problem, and the data-flow analysis and control-flow analysis are made co-dependent. We present a theoretical result which shows that a precise analysis of the transformed program, in the general case, is NP-hard and demonstrate the applicability of our techniques with empirical results.
On The Adequacy of Predicate Circumscription For Closed-World Reasoning
Authors: David W. Etherington, Robert E. Mercer, Raymond Reiter
Venue:  (1984)

We focus on McCarthy''s method of predicate circumscription in order to establish various results about its consistency, and about its ability to conjecture new information. A basic result is that predicate circumscription cannot account for the standard kinds of default reasoning. Another is that predicate circumscription yields no new information about the equality predicate. This has important consequences for the unique names and domain closure assumptions.
Computing Common Tangents Without a Separating Line
Authors: David Kirkpatrick, Jack Snoeyink
Venue:  (1994)

Given two disjoint convex polygons in standard representations, one can compute outer common tangents in logarithmic time without first obtaining a separating line. If the polygons are not disjoint, there is an additional factor of the logarithm of the intersection or union size, whichever is smaller.
Self-Adjusting Quorum Systems For Byzantine Fault Tolerance
Authors: Evelyn T Pierce
Venue:  (2001)

The purpose of this work has been to design protocols for a data service that tolerates Byzantine server faults by shifting between multiple tolerance modes at run time, monitoring itself for faulty server behavior and dynamically adjusting its own tolerance capabilities accordingly. Our goal is a system that runs in an efficient low-fault mode most of the time, but can adjust itself to cope with new faults as they occur. Our approach is based on the masking quorum systems of Malkhi and Reiter. Like the protocols originally proposed for these systems, our techniques are relatively economical in that updates and reads need to be performed only at a subset ("quorum") of data servers, thus decreasing the workload on individual servers and simplifying the recovery process when failures occur. However, our protocols implement the following additional capabilities: 1. Strengthened read and write protocols for serializability of completed operations. 2. Protocols for dynamically adjusting the threshold (and thus quorum size) of threshold masking quorum systems in response to information about the number and/or probability of faults in the system. 3. Protocols for detecting Byzantine server behavior in threshold masking quorum systems. As a subsidiary goal, we have sought to make our methods not only effective against random faulty server behavior, but also resistant to sabotage by a deliberate adversary. To this end, we have limited our use of standard assumptions, such as independence of failures and a priori limits on the number of faults, that restrict the applicability of many Byzantine fault tolerance techniques to questions of security.
Finite element simulation of post-elastic strain energy release rate for ductile thin wall structure
Authors: D. Tran
Venue: Proceedings of the eighth international conference on The application of artificial intelligence to civil and structural engineering computing (2001)

Great progress in design, analysis, and manufacturing-construction technology has often resulted in lighter and thinner structures. Fracture mechanics has contributed in better understanding and control of fracture, especially in fatigue fracture. For thin structures made of ductile material subjected to bursts of post-elastic loading, cracks may propagate considerably yet in a stable fashion. This crack extension, termed "stable tearing" is an increasingly important factor in the evaluation and control of fatigue crack in engineering structures subject to fatigue loading and intermittent overloading. An essential step in understanding stable tearing in thin ductile structures is the availability of G curves showing the relationship between strain energy release rate and the crack extension. These curves can be experimentally obtained in controlled laboratory testing of standard specimens containing simple cracks only. This paper looks at the alternative of obtaining G curves by finite element modeling and by virtual crack extension method, taking into account the non-linear plasticity of deformation. Singular elements were used to model the area near the crack front and the parametric design language of ANSYS 5.7 was used to generate G curves automatically. This FEM simulation of G curves would not only avoid tedious and expensive testing but also be applicable to a general structure having arbitrary cracks.
RECTANGLE REPLACEMENT AND VARIABLE ORDERING: TWO TECHNIQUES FOR LOGIC MINIMIZATION USING IF-THEN-ELSE DAGs (Ph.D. Thesis)
Authors: Soren Soe
Venue:  (1994)

This thesis explores logic minimization techniques for Boolean functions represented as if-then-else DAGs. In particular the thesis presents algorithms for two areas of multi-level logic minimization: Rectangle Covering and Variable Ordering. Rectangle covering is the process of factoring and extracting common sub-expressions in Boolean functions. Boolean functions are represented as Boolean matrices, and rectangles of these matrices represent either a factor of a function or a sub-expression that can be shared among several functions. An efficient heuristic algorithm two-column rectangle replacement for finding rectangles of a Boolean matrix is presented. The heuristic is particular well suited for optimizing circuits for area, while controlling the delay. A slight variation of the heuristic optimizes with respect to delay. Variable ordering is a problem specific to canonical if-then-else DAGs and ordered binary decision diagrams. This thesis presents an improved depth-first ordering heuristic based on reconvergent fanout. This heuristic is fast and produces variable orders resulting in smaller canonical forms than previously published traversal-based ordering heuristics, and is suitable when using canonical form for verification purposes. The thesis also presents a new ordering heuristic called {\em SplitOrder}, which is especially well suited for finding good variable orders for ordered binary decision diagrams (OBDDs). SplitOrder constructs the variable order by building an OBDD top-down one level at a time, choosing the next variable such that the corresponding level in the OBDD has few nodes and represents expressions that are as small as possible. SplitOrder is compared to several depth-first ordering heuristics and show that when converting to OBDDs SplitOrder averages 25% fewer nodes than taking the best of 8 depth-first techniques (37% better than the best single depth-first technique). Finally it is demonstrated that applying SplitOrder to a set of expressions already represented as an OBDD often results in significantly better variable orders, thus making it beneficial to iterate SplitOrder. All of the algorithms presented in this thesis have been implemented, tested, and installed as part of the logic minimizer ITEM.
SAMOS an Active Object-Oriented Database System: Manual
Authors: Stella Gatziu, Hans Fritschi, Anca Vaduva
Venue:  (1996)

SAMOS is an active-object oriented DBMS prototype implemented at the University of Zurich. It is now operational and thus is among the first demonstrable active object-oriented DBMSs. The beta-release of SAMOS, version 1.0 is available in the public domain. This manual gives you instructions for installing SAMOS on your site. It discuss the main features of SAMOS and shows step-by-step how SAMOS can be used for implementing active applications.
Unparsing Expressions With Prefix and Postfix Operators
Authors: Norman Ramsey
Venue:  (1997)

Automatic generation of computer programs from high-level specifications is a well-known technique, which has been used to create scanners, parsers, code generators, tree rewriters, packet filters, dialogue handlers, machine-code recognizers, and other tools. To make it easier to debug an application generator, and to help convince prospective users that the generated code can be trusted, the generated code should be as idiomatic and readable as possible. It is therefore desirable, and sometimes essential, that the generated code use infix, prefix, and postfix operators, and that they be presented without unnecessary parentheses. This paper presents a method of automatically parenthesizing expressions that use prefix, postfix, and implicit operators; the method is compatible with automatic prettyprinting. The paper also shows how to parse expressions that use such operators. The parsing algorithm can be used even if operator precedences are not known at compile time, which means that it can be used with an arbitrary number of user-defined precedences.
Constructing Invariant Features by Averaging Techniques
Authors: Hanns Schulz-Mirbach
Venue:  (1994)

The paper presents algorithms for the construction of features which are invariant with respect to a given transformation group. The methods are based on integral calculus and are applicable to parametric groups (Lie groups) and finite groups as well. To illustrate the concepts we discuss in detail how to construct invariant features for the general linear group which is of importance in computer vision applications. We briefly mention how to combine the algorithms with Hilbert space techniques for the description of continuous signals. Finally we apply the presented methods to establish the existence of complete feature sets for arbitrary compact groups.
Free-Surface Conditions in the Realistic Animation of Liquids
Authors: William F. Gates
Venue:  (2002)

The realistic animation of liquids based on the dynamic simulation of free-surface flow requires appropriate conditions on the liquid-gas interface. These conditions can be painstaking to implement and are in general not unique. We present the conditions we use in our implementation of a fluid animation system and discuss our rationale behind them.
Software and Hardware Techniques for Efficient Polymorphic Calls
Authors: Karel Driesen
Venue:  (1999)

Object-oriented code looks different from procedural code. The main difference is the increased frequency of polymorphic calls. A polymorphic call looks like a procedural call, but where a procedural call has only one possible target subroutine, a polymorphic call can result in the execution of one of several different subroutines. The choice is made at run time, and depends on the type of the receiving object (the first argument). Polymorphic calls enable the construction of clean, modular code design. They allow the programmer to invoke operations on an object without knowing its exact type in advance. This flexibility incurs an overhead: in general, polymorphic calls must be resolved at run time. The overhead of this run time polymorphic call resolution can lead a programmer to sacrifice clarity of design for more efficient code, by replacing instances of polymorphic calls by several single-target procedural calls, removing run time polymorphism. This practice typically leads to a more rigid program structure and code duplication, increasing the short term effort required to build a functional prototype, and the long term effort of maintaining and adapting a program to changing needs. We study techniques to minimize the run-time cost of polymorphic calls. In the software domain, we minimize the memory overhead of table based implementations (message dispatch tables), which are most efficient in terms of number of instructions executed. In the hardware domain, we reduce the cycle cost of these instructions through indirect branch prediction. For reasonable transistor budgets, hit rates of more than 95% can be achieved. As a result, only one out of twenty polymorphic calls incurs significant cost at run time. Design of clear, maintainable and reusable code, as enabled by object-oriented technology, can thereby become less restrained by efficiency considerations. Only in very time-critical program segments should the programmer avoid the use of polymorphism. In other words, object-oriented code can become the norm rather than the exception. From our own experience in building software architectures, we consider this a Good Thing.
Newspaper Segmentation and Adopted Methods
Authors: Paul S Williams, Mike Alder
Venue:  (1995)

This technical paper deals with the segmentation of newspaper articles into the distinct regions of text (i.e. paragraphs), pictures and background. It has been written to gather and consolidate ideas for personal use. I''ll basically outline the aim in more detail, along with assumptions and methods of segmentation. The methods will be presented as generic methods, current hacks and standard methods which may be useful. Some material presented may have little to do with newspaper segmentation, but has been included for future reference and to organise ideas.
The Cost of Terminating Optimistic Parallel Discrete-Event Simulations
Authors: Vasant Sanjeevan, Marc Abrams
Venue:  (1992)

In a previous paper, we proposed seven algorithms for mechanically adding an arbitrary termination condition to a conservative-synchronous, non-terminating parallel simulation. Informal arguments about the performance of each algorithm were made, and the arguments were confirmed through measurement for four of these algorithms. The benchmark used was the simulation of a Torus network using the Bounded Lag protocol on a shared memory multiprocessor. In this paper, we report on the performance of the simulation of the same Torus network benchmark with the same four termination conditions using an optimistic protocol on a message-passing multiprocessor. We also report on the performance of a colliding pucks simulation with three additional termination conditions.
Ein helligkeitsbasiertes Stereoverfahren zur Tiefenschatzung
Authors: An Luo, Hans Burkhardt
Venue:  (1995)

In diesem Beitrag stellen wir ein neues helligkeitsbasiertes Stereoverfahren vor, das die Tiefen-Diskontinuit t und Okklusion beruecksichtigenkann. Zu wichtigen Themen werden die Einfluesse linearer und nichtlinearer Kamera- Verzerrung auf Tiefenschaetzung diskutiert und eine einfache Methode zur Kamera-Kalibrierung vorgestellt. Unser schwach-glattes MAP-Modell des Tiefenfeldes wird weiterhin verwendet und jedoch nur ein Tiefenfeld zentrisches Systems wird statt zwei Tiefenfelder der Kamerasysteme optimal geschaetzt, wobei zur Verminderung des Aufwandes die originalen zwei gegenseitigen Matchingprozesse vermieden werden. Der Algorithmus wird mit Mehrgitterverfahren implementiert und die Leistungsf higkeit wird durch reale Beispiele gezeigt.
Shape optimization problem for incompressible viscous flow based on optimal control theory
Authors: T. Ochiai, M. Kawahara
Venue: Proceedings of the eighth international conference on The application of artificial intelligence to civil and structural engineering computing (2001)

The purpose of this study is to caluculate a numerical application of a shape optimization formulation of a body located in an incompressible viscous flow field. The formulation is based on an optimal control theory in which a performance function is introduced. Shape optimization is to solve the surface coordinates of the body that minimizes a performance function. The performance function should be minimized satisfying the state equation. This problem can be transformed into the minimization problem without constraint condition by the lagrangian multiplier or the adjoint equations using adjoint variables corresponding to state variables of the state equations. In this paper the formulation and calculation of shape optimization problem in a Stokes flow with some constraint is presented. The performance function is defined by the fluid forces subjected to the
A limit analysis method for nailed earth slopes
Authors: Y. S. Hong
Venue: Proceedings of the eighth international conference on The application of artificial intelligence to civil and structural engineering computing (2001)

In this paper, a new stability analysis model based on the limit analysis concept for nailed earth slopes is presented. A plastic deformation mechanism that satisfies the boundary velocity conditions is assumed. By equating the external rate of work to the internal rate of dissipation in an assumed velocity field, a minimum safety factor and the corresponding critical slip surface can be obtained. The proposed model can be applied to vertical as well as non-vertical slopes using the method of slices. In order to promote calculating efficiency, the developed analysis model is implemented into a computer program called SASNS. Using this program to analyse a full-scale nailed wall built in France. The results are compared with the observation. The applicability of the proposed model has been proved in this paper.
Incremental Algorithms for Optimizing Model Computation Based on Partial Instantiation
Authors: Raymond T. Ng, Xiaomei Tian
Venue:  (1994)

It has been shown that mixed integer programming methods can effectively support minimal model, stable model and well-founded model semantics for ground deductive databases. Recently, a novel approach called partial instantiation has been developed which, when integrated with mixed integer programming methods, can handle non-ground logic programs. The goal of this paper is to explore how this integrated framework based on partial instantiation can be optimized. In particular, we develop an incremental algorithm that minimizes repetitive computations. We also develop several optimization techniques to further enhance the efficiency of our incremental algorithm. Experimental results indicate that our algorithm and optimization techniques can bring about very significant improvement in run-time performance.
The Inconsistency of Belief Revision System
Authors: George K. Tsiknis
Venue:  (1988)

In 1987 Chern Seet developed a belief revision algorithm and a deduction system by which, he claims, default reasoning can be accomplished. We show that his deduction system is inconsistent. Some obvious corrections are suggested but the resulting system is still inconsistent. Its behaviour is similar to that of a closed-world- assumption reasoner. We examine a case in which the modified system behaves like the predicate circumscription and also has a reasonable performance. Finally, we discuss some problems pertaining to Seet''s revision strategy. A similar revision algorithm for normal default logic is outlined and the use of the SET model for handling exceptions --- and default reasoning --- is briefly discussed.
Resource Management in Legion
Authors: Steve J. Chapin, Dimitrios Katramatos, John Karpovich, Andrew S. Grimshaw
Venue:  (1998)

The recent development of gigabit networking technology, combined with the proliferation of low-cost, high-performance microprocessors, has given rise to metacomputing environments. These environments can combine many thousands of hosts, from hundreds of administrative domains, connected by transnational and world-wide networks. Managing the resources in such a system is a complex task, but is necessary to efficiently and economically execute user programs. In this paper, we describe the resource management portions of the Legion metacomputing system, including the basic model and its implementation. These mechanisms are flexible both in their support for system-level resource management but also in their adaptability for user-level scheduling policies. We show this by implementing a simple scheduling policy and demonstrating how it can be adapted to more complex algorithms.
FSQL: a flexible query language for data mining
Authors: Ramón Alberto Carrasco, María Amparo Vila, José Galindo
Venue: Enterprise information systems IV (2003)

At present we have a FSQL server available for Oracle© Databases, programmed in PL/SQL. This server allows us to query a Fuzzy or Classical Database with the FSQL language (Fuzzy SQL). The FSQL language is an extension of the SQL language, which permits us to write flexible (or fuzzy) conditions in our queries to a fuzzy or traditional database. In this paper we show an extension of FDBR architecture of FSQL for fuzzy handling of different types of data. The main advantage is that any user can to define his own fuzzy comparator for any specific problem. We consider that this model satisfies the requirements of Data Mining systems (handling of different types of data, high-level language, efficiency, certainty, interactivity, etc) and this new level of personal configuration makes the system very useful and flexible.
An Effective Image Thresholding Method using a Fuzzy Compactness Measure
Authors: Wenjing Tao, Hans Burkhardt
Venue:  (1994)

This paper presents an improved method for image thresholding by optimization of fuzzy compactness which was originally introduced by Pal and Rosenfeld. In our method a set of asymmetric S-functions whose windows are located in the same range are used as membership functions for obtaining fuzzy compactness. This avoids the problem which may occur in the original algorithm by unsuitably choosing of window size. An effective algorithm for finding the optimum is developed which proved to be computationally faster. An application using this method to segment the regions of interesting of flame images is also demonstrated.
A LONGITUDINAL SURVEY OF INTERNET HOST RELIABILITY
Authors: Darrell Long, Andrew Muir, Richard Golding
Venue:  (1995)

An accurate estimate of host reliability is important for correct analysis of many fault-tolerance and replication mechanisms. In a previous study, we estimated host system reliability by querying a large number of hosts to find how long they had been functioning, estimating the mean time-to-failure (MTTF) and availability from those measures, and in turn deriving an estimate of the mean time-to-repair (MTTR). However, this approach had a bias towards more reliable hosts that could result in overestimating MTTR and underestimating availability. To address this bias we have conducted a second experiment, using a fault-tolerant replicated monitoring tool. This tool directly measures TTF, TTR, and availability by polling many sites frequently from several locations. We find that these more accurate results generally confirm and improve our earlier estimates. We also find that failure and repair are unlikely to follow Poisson processes.