ppxscal/embedding_network huggingface dataset:
Some Combinatorial Properties of Schubert Polynomials
Authors: Sara C. Billey, William Jockusch, Richard P. Stanley
Venue: Journal of Algebraic Combinatorics: An International Journal (1993)

Schubert polynomials were introduced by Bernstein et al. and Demazure, and were extensively developed by Lascoux, Sch&uuml;tzenberger, Macdonald, and others. We give an explicit combinatorial interpretation of the Schubert polynomial {\mathfrak S}_w in terms of the reduced decompositions of the permutation w. Using this result, a variation of Schensted's correspondence due to Edelman and Greene allows one to associate in a natural way a certain set {\cal M}_w of tableaux with w, each tableau contributing a single term to {\mathfrak S}_w. This correspondence leads to many problems and conjectures, whose interrelation is investigated. In Section 2 we consider permutations with no decreasing subsequence of length three (or 321-avoiding permutations). We show for such permutations that {\mathfrak S}_w is a flag skew Schur function. In Section 3 we use this result to obtain some interesting properties of the rational function s_{\lambda/\mu}(1,q,q^2,\cdots), where s_{\lambda/\mu} denotes a skew Schur function.
Semantics for null extended nested relations
Authors: Mark Levene, George Loizou
Venue: ACM Transactions on Database Systems (TODS) (1993)

The nested relational model extends the flat relational model by relaxing the first normal form assumption in order to allow the modeling of complex objects. Much of the previous work on the nested relational model has concentrated on defining the data structures and query language for the model. The work done on integrity constraints in nested relations has mainly focused on characterizing subclasses of nested relations and defining normal forms for nested relations with certain desirable properties. In this paper we define the semantics of nested relations, which may contain null values, in terms of integrity constraints, called null extended data dependencies, which extend functional dependencies and join dependencies encountered in flat relational database theory. We formalize incomplete information in nested relations by allowing only one unmarked generic null value, whose semantics we do not further specify. The motivation for the choice of a generic null is our desire to investigate only fundamental semantics which are common to all unmarked null types. This lead us to define a preorder on nested relations, which allows us to measure the relative information content of nested relations. We also define a procedure, called the extended chase procedure, for testing satisfaction of null extended data dependencies and for making inferences by using these null extended data dependencies. The extended chase procedure is shown to generalize the classical chase procedure, which is of major importance in flat relational database theory. As a consequence of our approach we are able to capture the novel notion of losslessness in nested relations, called herein null extended lossless decomposition. Finally, we show that the semantics of nested relations are a natural extension of the semantics of flat relations.
Passing large dynamic objects out of function frame boundaries: the temporary linked list method
Authors: Ahsan J. Sharafuddin, Nathan Ida, James E. Grover
Venue: ACM SIGPLAN Notices (1994)

It is a well known fact that passing objects into functions by reference (in C++) is more efficient than passing by value. Passing objects, created within functions, out of functions by reference could also be more efficient if it wasn't sure to cause memory-leak in the system. Programmers therefore resort to "pass-by-reference, return-by-value". Here we first briefly look at why it is important to be able to return by reference, particularly for large dynamic objects in mathematical applications, and then present a new scheme for doing so. The new method can attain efficiency comparable to that of 'method of reference counting', but without the undesirable side-effects of the latter.
The Subconstituent Algebra of an Association Scheme (Part III)
Authors: Paul Terwilliger
Venue: Journal of Algebraic Combinatorics: An International Journal (1993)

This is the continuation of an article from the previous issue. In this part, we focus on the thin P- and Q-polynomial association schemes. We provide some combinatorial characterizations of these objects and exhibit the known examples with diameter at least 6. For each example, we give the irreducible modules for the subconstituent algebra. We close with some conjectures and open problems.
An adaptive framework for dynamic access to bandwith at high speeds
Authors: Kerry W. Fendick, Manoel A. Rodrigues
Venue: Conference proceedings on Communications architectures, protocols and applications (1993)

Emerging technologies for high-speed data network provide users with explicit feedback about congestion. Users, however, have questioned whether feedback can help in avoiding congestion in wide-area networks that operate at speeds of multiple megabits- or gigabits-per-second. In this paper we analyze a class of adaptive schemes with delayed feedback, where adaptive sources interact with each other as well as with non-adaptive sources through a single queue. We model the network as a stochastic, delay-differential equation and the rate at which an adaptive source transmits data as a fluid. Our model accounts for different levels of traffic burstiness introduced by the non-adaptive sources and for distinct propagation delays for different adaptive sources. We show how the performance of the system scales with increasing network speeds for quite general fluctuations in the bandwidth available to the adaptive sources. Simulation results show the accuracy of the model's predictions as a function of key parameters. This paper should raise the expectations of users about the potential effectiveness of responding to congestion notification.
A query language for list-based complex objects
Authors: Latha S. Colby, Edward L. Robertson, Lawrence V. Saxton, Dirk Van Gucht
Venue: Proceedings of the thirteenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems (1994)

We present a language for querying list-based complex objects. The language is shown to express precisely the polynomial-time generic list-object functions. The iteration mechanism of the language is based on a new approach wherein, in addition to the list over which the iteration is performed, a second list is used to control the number of iteration steps. During the iteration, the intermediate results can be moved to the output list as well as reinserted into the list being iterated over. A simple syntactic constraint allows the growth rate of the intermediate results to be tightly controlled which, in turn, restricts the expressiveness of the language to PTIME.
Expert systems in government: a look at the redistricting problem
Authors: Stephen P. Leach, Abraham Kandel
Venue: ACM SIGAPP Applied Computing Review (1993)

The process of redistricting involves the division of a land surface into two or more pieces. In a political setting, the districts thus formed provide groups of voters that elect the same public officials. Other types of redistricting applications include the formation of school districts, transportation districts, or water management districts. In this work we describe a knowledge-based expert system, Grouper, as a solution to the redistricting problem. A number of key issues are addressed by the solution, including equality of population, contiguity, and graphical display of possible districts. In addition, we outline a method (the Grouper approach) for dramatically reducing the complexity of the redistricting problem by limiting activity to a specific level of detail. A PC-based, prototype solution, implemented using the M.1 expert system shell, is described with emphasis on techniques for minimizing search. An annotated Grouper session is included. Lastly, there is a discussion of the far-reaching significance of the redistricting problem and promising uses or extensions of the Grouper system in this regard.
Machine learning for a dynamic manufacturing environment
Authors: R. A. Perez, J. T. Lilkendey, S. W. Koh
Venue: ACM SIGICE Bulletin (1994)

Within the semiconductor wafer manufacturing process, tight quality control is of utmost importance. This is due to such factors as the highly competitive nature of the business [2] and the complex nature of the process itself. Therefore, it is imperative that processing problems are recognized and corrected as quickly as possible. To accomplish this, a Parametric Test facility exists where a critical quality check is performed on the wafers. This is accomplished by measuring a number of electrical parameters at existing test sites on the wafer. Each measurement must fall within an acceptable range of values for its associated parameter to pass the critical check. If test results indicate that a parameter is outside of its acceptable range, the wafer may fail the quality check and be scrapped. If this happens an expert must examine all the parametric data associated with that wafer and attempt to determine the reason for failure and where in the manufacturing process the problem may have occurred.
An evaluation system for distributed-time VHDL simulation
Authors: Alessandra Costa, Alessandro de Gloria, Paolo Faraboschi, Mauro Olivieri
Venue: ACM SIGSIM Simulation Digest (1994)

Performance of VHDL simulation is a critical issue in electronic circuit design and is hard to achieve due to the complexity of the language and the different abstraction levels. This paper presents a system for performance evaluation of distributed-time VHDL simulation based on the analysis of simulation traces. The system allows to model different architectures, interconnection topologies and simulation algorithms. The main tools are a VHDL analyzer to extract dependencies, and a trace-driven simulator to evaluate the execution time on a given architecture.
Object-oriented engineering of distributed applications (abstract)
Authors: Max Muhlhauser, Lutz Heuser
Venue: Addendum to the proceedings on Object-oriented programming systems, languages, and applications (Addendum) (1992)

The Universities of Kaiserlautern and Karlsruhe are cooperating with the CEC Karlsruhe, a research center of Digital Equipment CmbH, in the area of software engineering for distributed applications. This demonstration will showcase DOCASE, a software engineering environment for distributed applications, using object-oriented technology. The demonstration will provide insight into the methods, languages, tools and environments used in the life-cycle of distributed applications. With the term distributed applications, we put an emphasis on structured parallelism (which comes more or less naturally with the logical structure and inherent parallelism and distribution of an application), not so much on the fine-grained parallelism exploited by applications such as image processing etc. With more and more complex (dynamic, multiparty, cooperative) distributed applications to be developed in computer integrated manufacturing, office automation, CSCW, and other domains, we think that this topic is both very much up to date and a topic which is not sufficiently taught. The live demonstration will show a distributed application which will allow researchers of arbitrary disciplines to coordinate their work with other members of a research team. The underlying meta model is generic and instantiated by developing a set of concrete object types together with a GUI.
Compiler and runtime support for out-of-core HPF programs
Authors: Rajeev Thakur, Rajesh Bordawekar, Alok Choudhary
Venue: Proceedings of the 8th international conference on Supercomputing (1994)

This paper describes the design of a compiler which can translate out-of-core programs written in a data parallel language like HPF. Such a compiler is required for compiling large scale scientific applications, such as the Grand Challenge applications, which deal with enormous quantities of data. We propose a framework by which a compiler together with appropriate runtime support can translate an out-of-core HPF program to a message passing node program with explicit parallel I/O. We describe the basic model of the compiler and the various transformations made by the compiler. We also discuss the runtime routines used by the compiler for I/O and communication. In order to minimize I/O, the runtime support system can reuse data already fetched into memory. The working of the compiler is illustrated using two out-of-core applications, namely a Laplace equation solver and LU Decomposition, together with performance results on the Intel Touchstone Delta.
Collaborative plan construction for multiagent mutual planning (abstract)
Authors: Ei-Ichi Osawa, Mario Tokoro
Venue: ACM SIGOIS Bulletin (1992)

Representation can be critical in enabling agents to interact effectively. Alternative methods for representing and reasoning about the world can radically affect the ability of agents to reach cooperative solutions. Focal points are examined as a particularly compelling example of the importance of representation. We consider the algorithms that might be used by resource-constrained agents in discovering prominent solutions of their interaction. The primary tool for our investigation is step logic [5].
Interface definition language conversions: recursive types
Authors: David E. Gay
Venue: Proceedings of the workshop on Interface definition languages (1994)

A large heterogeneous network contains many applications developed in different environments, each with its own incompatible interface definition language. One way of dealing with this diversity is to define a conversion from the interfaces of one system into another, thus giving access from the second system to the first. This presents a number of difficulties, amongst which is the different representation of recursive types in different languages. This paper gives two algorithms for converting the representation of such recursive types between different styles of interface definition languages.
The power of sampling in knowledge discovery
Authors: Jyrki Kivinen, Heikki Mannila
Venue: Proceedings of the thirteenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems (1994)

We consider the problem of approximately verifying the truth of sentences of tuple relational calculus in a given relation M by considering only a random sample of M. We define two different measures for the error of a universal sentence in a relation. For a set of n universal sentences each with at most k universal quantifiers, we give upper and lower bounds for the sample sizes required for having a high probability that all the sentences with error at least &egr; can be detected as false by considering the sample. The sample sizes are O((log n)/&egr;) or O((|M|1&ndash;1/k)log n/&egr;), depending on the error measure used. We also consider universal-existential sentences.
Local verification of global integrity constraints in distributed databases
Authors: Ashish Gupta, Jennifer Widom
Venue: Proceedings of the 1993 ACM SIGMOD international conference on Management of data (1993)

We present an optimization for integrity constraint verification in distributed databases. The optimization allows a global constraint, i.e. a constraint spanning multiple databases, to be verified by accessing data at a single database, eliminating the cost of accessing remote data. The optimization is based on an algorithm that takes as input a global constraint and data to be inserted into a local database. The algorithm produces a local condition such that if the local data satisfies this condition then, based on the previous satisfaction of the global constraint, the global constraint is still satisfied. If the local data does not satisfy the condition, then a conventional global verification procedure is required.
Extending the scope of database services
Authors: Daniel Barbará
Venue: ACM SIGMOD Record (1993)

A wide variety of important data remains outside of the scope of database management systems. In recent years researchers have been making efforts in two directions: first, developing database management systems that can support non-traditional data, and secondly, offering database services for data that remains under control of autonomous (not necessarily database) systems. The purpose of this paper is to provide a brief review of these efforts.
pGVT: an algorithm for accurate GVT estimation
Authors: Loy M. D'Souza, Xianzhi Fan, Philip A. Wilsey
Venue: ACM SIGSIM Simulation Digest (1994)

The time warp mechanism uses memory space to save event and state information for rollback processing. As the simulation advances in time, old state and event information can be discarded and the memory space reclaimed. This reclamation process is called fossil collection and is guided by a global time value called Global Virtual Time (GVT). That is, GVT represents the greatest minimum time of the fully committed events (the time before which no rollback will occur). GVT is then used to establish a boundary for fossil collection. This paper presents a new algorithm for GVT estimation called pGVT. pGVT was designed to support accurate estimates of the actual GVT value and it operates in an environment where the communication subsystem does not support FIFO message delivery and where message delivery failure may occur. We show that pGVT correctly estimates GVT values and present some performance comparisons with other GVT algorithms.
Using lifetime predictors to improve memory allocation performance
Authors: David A. Barrett, Benjamin G. Zorn
Venue: Proceedings of the ACM SIGPLAN 1993 conference on Programming language design and implementation (1993)

Dynamic storage allocation is used heavily in many application areas including interpreters, simulators, optimizers, and translators. We describe research that can improve all aspects of the performance of dynamic storage allocation by predicting the lifetimes of short-lived objects when they are allocated. Using five significant, allocation-intensive C programs, we show that a great fraction of all bytes allocated are short-lived (> 90% in all cases). Furthermore, we describe an algorithm for liftetime prediction that accurately predicts the lifetimes of 42&ndash;99% of all objects allocated. We describe and simulate a storage allocator that takes adavantage of lifetime prediction of short-lived objects and show that it can significantly improve a program's memory overhead and reference locality, and even, at times, improve CPU performance as well.
Twisted data layout
Authors: Tatsuya Shindo, Hidetoshi Iwashita, Shaun Kaneshiro, Tsunehisa Doi, Junichi Hagiwara
Venue: Proceedings of the 8th international conference on Supercomputing (1994)

This paper proposes twisted data layout as a novel and efficient data layout technique for distributed memory parallel processors (DMPP). Data layout is an important aspect in efficiently executing a parallel program on DMPPs. The optimal data layout pattern for an array may differ throughout the program. Twisted data layout can be used to resolve the conflicts among the optimal array distributions in a special case. Experimental results on the AP1000 multicomputer measure the performance of the twisted data layout scheme.
SPIDER: a multiuser information retrieval system for semistructured and dynamic data
Authors: Peter Schäuble
Venue: Proceedings of the 16th annual international ACM SIGIR conference on Research and development in information retrieval (1993)

The access structure, the retrieval model, and the system architecture of the SPIDER information retrieval system are described. The access structure provides efficient weighted retrieval on dynamic data collections. It is based on signatures and non-inverted item descriptions. The signatures provide upper bounds for the exact retrieval status values such that only a small number of exact retrieval status values have to be computed. SPIDER's retrieval model is a probabilistic retrieval model that is capable to exploit the database scheme of semistructured data collections. This model can be considred as a further development of the Binary Independence Indexing (BII) model. The system architecture was derived systematically from a given set of requirements such as effective and efficient retrieval on dynamic data collections, exploitation of the database scheme, computed views, and the integration of information retrieval functionality and database functionality.
Inheritance of interface specifications (extended abstract)
Authors: Gary T. Leavens
Venue: ACM SIGPLAN Notices (1994)

Four alternatives for the semantics of inheritance of specifications are discussed. The information loss and frame axiom problems for inherited specifications are also considered.
Structured APL: a proposal for block structured control flow in APL
Authors: Robert G. Willhoft
Venue: ACM SIGAPL APL Quote Quad (1993)

APL, although a very powerful language, has failed to gain wide acceptance in part due to its lack of control structures. A proposal is made for introducing structure in APL objects by adding to the items that can be located on the left of the colon (:). These markers show the beginning and ends of blocks of code and allow for selection, iteration, and termination. The set of control structures is shown to be robust by showing their use in the creation of traditional control structures. A method of conversion to ISO APL is also presented.This paper briefly discusses proposals that have been made in the past along with an evaluation of their merits and shortcomings. The paper ends with a discussion of related issues, including elimination of branching, introduction of definition blocks, and lexical scoping in APL. Several areas for continuing work are given.
Simulating synchronized clocks and common knowledge in distributed systems
Authors: Gil Neiger, Sam Toueg
Venue: Journal of the ACM (JACM) (1993)

Time and knowledge are studied in synchronous and asynchronous distributed systems. A large class of problems that can be solved using logical clocks as if they were perfectly synchronized clocks is formally characterized. For the same class of problems, a broadcast primitive that can be used as if it achieves common knowledge is also proposed. Thus, logical clocks and the broadcast primitive simplify the task of designing and verifying distributed algorithms: The designer can assume that processors have access to perfectly synchronized clocks and the ability to achieve common knowledge.
A restricted crossbar implementation and its applications
Authors: Thomas Beth, Volker Hatz
Venue: ACM SIGARCH Computer Architecture News (1991)

In this article a new concept for permutation devices is shown. Such devices, like crossbars, are used within connection networks for parallel computers.The idea shown here is to partition the complete graph with n vertices into n minus; 1 different partitions and to switch very fast between these partitions, so that the user sees a complete graph structure. Finally a compact VLSI layout is described which can be easily implemented using automatic design tools.
Deadlock prevention in a distributed database system
Authors: P. Krishna Reddy, Subhash Bhalla
Venue: ACM SIGMOD Record (1993)

The distributed locking based approaches to concurrency control in a distributed database system, are prone to occurrence of deadlocks. An algorithm for deadlock prevention has been considered in this proposal. In this algorithm, a transaction is executed by forming wait for relations with other conflicting transactions. The technique for generation of this kind of precedence graph for transaction execution is analyzed. This approach is a fully distributed approach. The technique is free from deadlocks, avoids resubmission of transactions, and hence reduces processing delays within the distributed environment.