ppxscal/embedding_network huggingface dataset:
The Complexity and Distribution of Hard Problems
Authors: David W. Juedes, Jack H. Lutz
Venue: SIAM Journal on Computing (1995)

Measure-theoretic aspects of the $\leq^{\rm P}_{\rm m}$-reducibility structure of the exponential time complexity classes E=DTIME($2^{\rm linear}$) and $E_{2}={\rm DTIME}(2^{\rm polynomial})$ are investigated. Particular attention is given to the complexity (measured by the size of complexity cores) and distribution (abundance in the sense of measure) of languages that are $\leq^{\rm P}_{\rm m}$-hard for E and other complexity classes. Tight upper and lower bounds on the size of complexity cores of hard languages are derived. The upper bound says that the $\leq^{\rm P}_{\rm m}$-hard languages for E are unusually simple, in the sense that they have smaller complexity cores than most languages in E. It follows that the $\leq^{\rm P}_{\rm m}$-complete languages for E form a measure 0 subset of E (and similarly in $E_2$). This latter fact is seen to be a special case of a more general theorem, namely, that {\it every} \pmr-degree (e.g., the degree of all \pmr-complete languages for NP) has measure 0 in E and in \Ep.
Plant design for efficiency using AutoCAD and FactoryFLOW
Authors: David P. Sly
Venue: Proceedings of the 27th conference on Winter simulation (1995)

Designing industrial facilities in AutoCAD is very different from designing the office and laboratory environments typically discussed at AEC-oriented shows and seminars. In factories the cost of moving equipment and automated material handling systems is significant, making their initial placement critical. In addition, factories are designed for the optimal flow of materials, which requires a significant quantitative review and can be very time consuming and difficult to present. This paper discusses the systematic approach to the design of industrial facilities and how this approach can be greatly simplified with the use of such tools as AutoCAD with FactoryFLOW.
A probabilistic relational model and algebra
Authors: Debabrata Dey, Sumit Sarkar
Venue: ACM Transactions on Database Systems (TODS) (1996)

Although the relational model for databases provides a great range of advantages over other data models, it lacks a comprehensive way to handle incomplete and uncertain data. Uncertainty in data values, however, is pervasive in all real-world environments and has received much attention in the literature. Several methods have been proposed for incorporating uncertain data into relational databases. However, the current approaches have many shortcomings and have not established an acceptable extension of the relational model. In this paper, we propose a consistent extension of the relational model. We present a revised relational structure and extend the relational algebra. The extended algebra is shown to be closed, a consistent extension of the conventional relational algebra, and reducible to the latter.
The third manifesto
Authors: Hugh Darwen, C. J. Date
Venue: ACM SIGMOD Record (1995)

We present a manifesto for the future direction of data and database management systems. The manifesto consists of a series of prescriptions, proscriptions, and "very strong suggestions."
A super scalar sort algorithm for RISC processors
Authors: Ramesh C. Agarwal
Venue: ACM SIGMOD Record (1996)

The compare and branch sequences required in a traditional sort algorithm can not efficiently exploit multiple execution units present in currently available high performance RISC processors. This is because of the long latency of the compare instructions and the sequential algorithm used in sorting. With the increased level of integration on a chip, this trend is expected to continue. We have developed new sort algorithms which eliminate almost all the compares, provide functional parallelism which can be exploited by multiple execution units, significantly reduce the number of passes through keys, and improve data locality. These new algorithms outperform traditional sort algorithms by a large factor.For the Datamation disk to disk sort benchmark (one million 100-byte records), at SIGMOD'94, Chris Nyberg et al presented several new performance records using DEC alpha processor based systems.We have implemented the Datamation sort benchmark using our new sort algorithm on a desktop IBM RS/6000 model 39H (66.6 MHz) with 8 IBM SSA 7133 disk drives (total cost $73K). The total elapsed time for the 100 MB sort was 5.1 seconds (vs the old uni-processor record of 9.1 seconds). We have also established a new price performance record (0.2 cent; vs the old record of 0.9 cent;, as the cost of the sort). The entire sort processing was overlapped with I/O. During the read phase, we achieved a sustained BW of 47 MB/sec and during the write phase, we achieved a sustained BW of 39 MB/sec. Key extraction and sorting of one million 10-byte keys took only 0.6 second of CPU time. The rest of the CPU time was used in moving records, servicing I/O, and other overheads.Algorithmic details leading to this level of performance are described in this paper. A detailed analysis of the CPU time spent during various phases of the sort algorithm and I/O is also provided.
Convergence in Distribution for Best Fit-Decreasing
Authors: WanSoo T. Rhee, Michel Talagrand
Venue: SIAM Journal on Computing (1996)

Consider independent random variables $X_1, \dots, X_n$ uniformly distributed over $[0,1]$, and denote by $B_n$ the number of bins needed to pack items of these sizes using the best fit decreasing algorithm. We prove that the random variable $n^{-1/2}$ converges in distribution to a nonnormal limit. The method consists of showing that the patterns created by the algorithm exhibit some kind of convergence.
Practical parallel algorithms for personalized communication and integer sorting
Authors: David A. Bader, David R. Helman, Joseph JáJá
Venue: Journal of Experimental Algorithmics (JEA) (1996)

A fundamental challenge for parallel computing is to obtain high-level, architecture independent, algorithms which efficiently execute on general-purpose parallel machines. With the emergence of message passing standards such as MPI, it has become easier to design efficient and portable parallel algorithms by making use of these communication primitives. While existing primitives allow an assortment of collective communication routines, they do not handle an important communication event when most or all processors have non-uniformly sized personalized messages to exchange with each other. We focus in this paper on the h-relation personalized communication whose efficient implementation will allow high performance implementations of a large class of algorithms. While most previous h-relation algorithms use randomization, this paper presents a new deterministic approach for h-relation personalized communication with asymptotically optimal complexity for h>p2. As an application, we present an efficient algorithm for stable integer sorting. The algorithms presented in this paper have been coded in Split-C and run on a variety of platforms, including the Thinking Machines CM-5, IBM SP-1 and SP-2, Cray Research T3D, Meiko Scientific CS-2, and the Intel Paragon. Our experimental results are consistent with the theoretical analysis and illustrate the scalability and efficiency of our algorithms across different platforms. In fact, they seem to outperform all similar algorithms known to the authors on these platforms.
The Parti-game Algorithm for Variable Resolution Reinforcement Learning in Multidimensional State-spaces
Authors: Andrew W. Moore, Christopher G. Atkeson
Venue: Machine Learning (1995)

Parti-game is a new algorithm for learning feasible trajectories to goal regions in high dimensional continuous state-spaces. In high dimensions it is essential that neither planning nor exploration occurs uniformly over a state-space. Parti-game maintains a decision-tree partitioning of state-space and applies techniques from game-theory and computational geometry to efficiently and adaptively concentrate high resolution only on critical areas. The current version of the algorithm is designed to find feasible paths or trajectories to goal regions in high dimensional spaces. Future versions will be designed to find a solution that optimizes a real-valued criterion. Many simulated problems have been tested, ranging from two-dimensional to nine-dimensional state-spaces, including mazes, path planning, non-linear dynamics, and planar snake robots in restricted spaces. In all cases, a good solution is found in less than ten trials and a few minutes.
Distributed Synchronous Clocking
Authors: Gill A. Pratt, John Nguyen
Venue: IEEE Transactions on Parallel and Distributed Systems (1995)

It has historically been difficult to distribute a well-aligned hardware clock throughout the physical extent of a synchronous processor. Traditionally, this task has been accomplished by distributing the output of a central oscillator over a tree-like network, with repeaters at necessary intervals. While straightforward in concept, this method suffers from poor reliability, poor scalability and high skew. In this paper, we present an alternative approach¿Distributed Synchronous Clocking¿that maintains the simplicity of synchronous operation without suffering the drawbacks of centralized clocking. A network of independent oscillators takes the place of the centralized clock source, providing separate clock signals to the physically distant parts of a computing system. A distributed error correction algorithm effects global phase alignment by utilizing local comparisons of neighboring oscillator phase. In contrast to centralized clock distribution, distributed clocking has the inherent potential for complete scalability and graceful degradation. However, because oscillator phase is a modular quantity, a naive implementation of distributed synchronous clocking can suffer from mode-lock¿the trapping of local oscillator phase in undesirable stable equilibria where global phase is not aligned [26]. We present a simple method for eliminating this problem in $k$-ary Cartesian meshes and give a proof of its correctness for two-dimensional networks. An electronic implementation is also presented and several engineering issues relating to error tolerance are discussed.Index Terms¿Computer hardware clocking, clock synchronization, distributed clocking, oscillator synchronization, phase-locked loops, mode-locking.
Regularity Conditions for the Stability Margin Problem with Linear Dependent Perturbations
Authors: Antonio Vicino, Alberto Tesi
Venue: SIAM Journal on Control and Optimization (1995)

In this paper, the problem of continuity of the stability margin of a control system on problem input data is addressed. The case in which perturbations are linearly correlated is considered. It is shown that the existence of special points (called critical points) in the stability boundary manifold in parameter space plays a key role in the analysis of the problem. Several conditions, either sufficient or both necessary and sufficient, are given, ensuring continuity of the stability margin on problem data. The obtained conditions turn out to be easily checkable for practical applications. Numerical examples are presented to illustrate the proposed techniques.
Computing programs in small colleges
Authors: John Beidler, Richard H. Austing, Lillian N. Cassel
Venue: Communications of the ACM (1985)

This Summary Report of The ACM Small College Task Force outlines resources, courses, and problems for small colleges developing degree programs in computing.
Multiple-valued complex functions and computer algebra
Authors: Helmer Aslaksen
Venue: ACM SIGSAM Bulletin (1996)

I recently taught a course on complex analysis. That forced me to think more carefully about branches. Being interested in computer algebra, it was only natural that I wanted to see how such programs dealt with these problems. I was also inspired by a paper by Stoutemyer ([3]).While programs like Derive, Maple, Mathematica and Reduce are very powerful, they also have their fair share of problems. In particular, branches are somewhat of an Achilles' heel for them. As is well-known, the complex logarithm function is properly defined as a multiple-valued function. And since the general power and exponential functions are defined in terms of the logarithm function, they are also multiple valued. But for actual computations, we need to make them single valued, which we do by choosing a branch. In Section 2, we will consider some transformation rules for branches of multiple-valued complex functions in painstaking detail.The purpose of this short article is not to do a comprehensive comparative study of different computer algebra system. (For an attempt at that, see [4].) My goal is simply to make the readers aware of some of the problems, and to encourage the readers to sit down and experiment with their favourite programs.I would like to thank Willi-Hans Steeb and Michael Wester for helpful comments.
A Study of Theoretical Issues in the Synthesis of Delay Fault Testability Circuits
Authors: Sreejit Chakravarty
Venue: IEEE Transactions on Computers (1996)

Multilevel Logic Optimization Transformations used in existing logic synthesis systems are characterized with respect to their testability preserving and testability enhancing properties. A sufficient condition for a multilevel unate circuit to be "hazard free delay fault testable" is presented. In contrast to existing results that consider either "single path propagating hazard free robust tests" or "general robust tests" we consider "multiple path propagating hazard free robust tests" in our analysis.
Simulation-based real-time scheduling: review of recent developments
Authors: Catherine M. Harmonosky
Venue: Proceedings of the 27th conference on Winter simulation (1995)

With increased usage of computer monitoring of the factory has come increased industrial and academic interest in developing more science-based real-time scheduling techniques. Simulation, best known for its application during system design or modification, is also being considered for use on day-to-day scheduling problems. This paper reviews recent developments using simulation as a tool in real-time scheduling.
Reducing TLB and memory overhead using online superpage promotion
Authors: Theodore H. Romer, Wayne H. Ohlrich, Anna R. Karlin, Brian N. Bershad
Venue: Proceedings of the 22nd annual international symposium on Computer architecture (1995)

Modern microprocessors contain small TLBs that maintain a cache of recently used translations. A TLB's coverage is the sum of the number of bytes mapped by each entry. Applications with working sets larger than the TLB coverage will perform poorly due to high TLB miss rates. Superpages have been proposed as a mechanism for increasing TLB coverage. A superpageis a virtual memory page with size and alignment that are a power of two multiple of the system's base page size. In this paper, we describe online policies for superpage management that monitor TLB miss traffic to decide when a superpage should be constructed. Our policies take into account both the benefit of a superpage promotion (potential for preventing future misses) and the cost (page copying). Although our approach increases the cost of each TLB miss, the net effect is to improve total execution time by eliminating a large number of misses without significantly increasing memory usage, thereby improving system performance.
An Economic Model to Estimate Software Rewriting and Replacement Times
Authors: Taizan Chan, Siu-Leung Chung, Teck Hua Ho
Venue: IEEE Transactions on Software Engineering (1996)

The effort required to service maintenance requests on a software system increases as the software system ages and deteriorates. Thus, it may be economical to replace an aged software system with a freshly written one to contain the escalating cost of maintenance. We develop a normative model of software maintenance and replacement effort that enables us to study the optimal policies for software replacement. Based on both analytical and simulation solutions, we determine the timings of software rewriting and replacement, and hence the schedule of rewriting, as well as the size of the rewriting team as functions of the 1) user environment, 2) effectiveness of rewriting, 3) technology platform, 4) development quality, 5) software familiarity, and 6) maintenance quality of the existing and the new software systems. Among other things, we show that a volatile user environment often leads to a delayed rewriting and an early replacement (i.e., a compressed development schedule). On the other hand, a greater familiarity with either the existing or the new software system allows for a less-compressed development schedule. In addition, we also show that potential savings from rewriting will be higher if the new software system is developed with a superior technology platform, if programmers' familiarity with the new software system is greater, and if the software system is rewritten with a higher initial quality.
The SPIFFI scalable video-on-demand system
Authors: Craig S. Freedman, David J. DeWitt
Venue: Proceedings of the 1995 ACM SIGMOD international conference on Management of data (1995)

This paper presents a simulation study of a video-on-demand system. We present video server algorithms for real-time disk scheduling, prefetching, and buffer pool management. The performance of these algorithms is compared against the performance of simpler algorithms such as elevator and round-robin disk scheduling and global LRU buffer pool management. Finally, we show that the SPIFFI video-on-demand system scales nearly linearly as the number of disks, videos, and terminals is increased.
Classroom presentation of memory usage with constants, variables, and subprograms in Pascal
Authors: Edward J. O'Neill
Venue: ACM SIGCSE Bulletin (1995)

An essential part of the CS 1 course based on Pascal is the idea of random access memory usage when structured programs are executed. A survey of several texts reveals that the view of both variables and constants as memory locations for data is in many cases not systematically carried over and developed further when procedures and functions are presented. This paper presents a systematic method for understanding memory usage when dealing with subprograms in Pascal and presents a survey of current approaches.
Sublinear-space evaluation algorithms for attribute grammars
Authors: Thomas Reps, Alan Demers
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1987)

A major drawback of attribute-grammar-based systems is that they are profligate consumers of storage. This paper concerns new storage-management techniques that reduce the number of attribute values retained at any stage of attribute evaluation; it presents an algorithm for evaluating an n-attribute tree that never retains more than O(log n) attribute values. This method is optimal, although it may require nonlinear time. A second algorithm, which never retains more than O(n) attribute values, is also presented, both as an introduction to the O(log n) method and because it works in linear time.
Parallelizing the phylogeny problem
Authors: Jeff A. Jones, Katherine A. Yelick
Venue: Proceedings of the 1995 ACM/IEEE conference on Supercomputing (CDROM) (1995)

The problem of determining the evolutionary history of species in the form of phylogenetic trees is known as the phylogeny problem. We present a parallelization of the character compatibility method for solving the phylogeny problem. Abstractly, the algorithm searches through all subsets of characters, which may be traits like opposable thumbs or DNA sequence values, looking for a maximal consistent subset. The notion of consistency in this case is the existence of a particular kind of phylogenetic tree called a perfect phylogeny tree. The two challenges to achieving an efficient implementation are load balancing and efficient sharing of information to enable pruning. In both cases, there is a trade-off between communication overhead and the quality of the solution. For load balancing we use a distributed task queue, which has imperfect load information but avoids centralization bottlenecks. For sharing pruning information, we use a distributed trie, which also avoids centralization but maintains incomplete information. We evaluate several implementations of the trie, the best of which achieves speedups of 50 on a 64-processor CM-5.
Algorithm 646: PDFIND: a routine to find a positive definite linear combination of two real symmetric matrices
Authors: Charles R. Crawford
Venue: ACM Transactions on Mathematical Software (TOMS) (1986)

PDFIND is a FORTRAN-77 implementation of an algorithm that finds a positive definite linear combination of two symmetric matrices, or determines that such a combination does not exist. The algorithm is designed to be independent of the data structures used to store the matrices. The user must provide a subroutine, CHLSKY, which acts as an interface between PDFIND and the matrix data structures. CHLSKY also provides the user control over the number of iterations of the algorithm. Implementations of CHLSKY are included which call LINPAC routines for full matrices as well as symmetric banded matrices.
Enriching the lambda calculus with contexts: toward a theory of incremental program construction
Authors: Shinn-Der Lee, Daniel P. Friedman
Venue: Proceedings of the first ACM SIGPLAN international conference on Functional programming (1996)

A context in the lambda;-calculus is a term with some holes. Hole filling differs from beta;-substitution in that name capture is intended. This seemingly simple feature transcends static scope and lies at the heart of modular and object-oriented programming. Still, the name capture feature of hole filling is at odds with hygienic beta;-substitution. In this paper we conservatively extend the lambda;-calculus to incorporate the notion of contexts without jeopardizing the beta;-rule. We perceive contexts as source code and lambda;-terms as target code. Context filling is encoded as compilation operations and the enriched calculus is a theory of separate compilation and incremental program construction. Linking of separately-developed programs is done by coherent renaming of free variables.We apply our context-enriching schema to the lambda;-calculus extended with definitions and devise a calculus of first-class modules. We show that module linking can be modeled solely by the renaming of import and export variables. We add relinkable variable references to model virtual method references essential to object systems.The inclusion of contexts introduces parameters whose linking is based on names (symbols, identifiers, or keywords). We simulate in the context-enriched calculus other extensions of the lambda;-calculus with name-based programming notions such as Dami's lambda;-calculus with names, A iuml;t-Kaci and Garrigue's label-selective lambda;-calculus, Lamping's transparent data parameters, and our quasi-static procedures.