... letters of the last names of its authors – Alfred Aho, Peter Weinberger, and Brian Kernighan) scripts. Send an ...
Tópico(s): Soil Carbon and Nitrogen Dynamics
2014 - United States Geological Survey | Data series
... to the Ubiquity symposium discussing What is computation? Alfred V. Aho shares his views about the importance of computational ...
Tópico(s): DNA and Biological Computing
2011 - Association for Computing Machinery | Ubiquity
... talk Share on Teaching the compilers course Author: Alfred V. Aho Columbia University, New York, New York Columbia University, ...
Tópico(s): Educational Technology and Assessment
2008 - Association for Computing Machinery | ACM SIGCSE Bulletin
Alfred V. Aho, Peter J. Denning, Jeffrey D. Ullman,
article Free AccessPrinciples of Optimal Page Replacement Authors: Alfred V. Aho Bell Telephone Laboratories, Inc., Murray Hill, New Jersey ...
Tópico(s): ICT Impact and Policies
1971 - Association for Computing Machinery | Journal of the ACM
... Free Access Share on Nested Stack Automata Author: Alfred V. Aho Bell Telephone Laboratories, Inc., Murray Hill, New Jersey ...
Tópico(s): DNA and Biological Computing
1969 - Association for Computing Machinery | Journal of the ACM
Alfred V. Aho, Jeffrey D. Ullman,
Jeffrey D. Ullman and Alfred V. Aho are recipients of the 2020 ACM A.M. Turing award. They were recognized for creating fundamental algorithms and theory underlying ...
Tópico(s): Graph Theory and Algorithms
2022 - Association for Computing Machinery | Communications of the ACM
We recommend using the term Computation in conjunction with a well-defined model of computation whose semantics is clear and which matches the problem being investigated. Computer science already has a number of useful clearly defined models of computation whose behaviors and capabilities are well understood. We should use such models as part of any definition of the term computation. However, for new domains of investigation where there are no appropriate models it may be necessary to invent new ...
Tópico(s): DNA and Biological Computing
2012 - Oxford University Press | The Computer Journal
Marc Eaddy, Thomas Zimmermann, Kaitlin Duck Sherwood, Vedant Garg, Gail C. Murphy, Nachiappan Nagappan, Alfred V. Aho,
There is a growing consensus that crosscutting concerns harm code quality. An example of a crosscutting concern is a functional requirement whose implementation is distributed across multiple software modules. We asked the question, "How much does the amount that a concern is crosscutting affect the number of defects in a program?" We conducted three extensive case studies to help answer this question. All three studies revealed a moderate to strong statistically significant correlation between the ...
Tópico(s): Advanced Malware Detection Techniques
2008 - IEEE Computer Society | IEEE Transactions on Software Engineering
Krysta M. Svore, Andrew W. Cross, Isaac L. Chuang, Alfred V. Aho,
An arbitrarily reliable quantum computer can be efficiently constructed from noisy components using a recursive simulation procedure, provided that those components fail with probability less than the fault-tolerance threshold. Recent estimates of the threshold are near some experimentally achieved gate fidelities. However, the landscape of threshold estimates includes pseudothresholds, threshold estimates based on a subset of components and a low level of the recursion. In this paper, we observe ...
Tópico(s): Computability, Logic, AI Algorithms
2006 - Rinton Press | Quantum Information and Computation
Krysta M. Svore, Alfred V. Aho, Andrew W. Cross, Isaac L. Chuang, Igor L. Markov,
Compilers and computer-aided design tools are essential for fine-grained control of nanoscale quantum-mechanical systems. A proposed four-phase design flow assists with computations by transforming a quantum algorithm from a high-level language program into precisely scheduled physical actions.
Tópico(s): Quantum-Dot Cellular Automata
2006 - IEEE Computer Society | Computer
... J. Wilson Graph Representation Computer Representation of Graphs, Alfred V. Aho Graph Isomorphism, Brendan D. McKay The Reconstruction Problem, ...
Tópico(s): Graph Labeling and Dimension Problems
2005 - Association of College and Research Libraries | Choice Reviews Online
Alfred V. Aho, Shih‐Fu Chang, Kathleen McKeown, Dragomir Radev, John R. Smith, Kazi A. Zaman,
In this paper we describe an ongoing research project called the Columbia Digital News Project. The goal of this project is to develop a suite of effective interoperable tools with which people can find relevant information (text, images, video, and structured documents) from distributed sources and track it over a period of time. Our initial focus is on the development of a system with which researchers, journalists, and students can keep track of current news events in specific areas.
Tópico(s): Advanced Image and Video Retrieval Techniques
1998 - Springer Science+Business Media | International Journal on Digital Libraries
Alfred V. Aho, Anton Dahbura, D. Lee, M. Ümit Uyar,
A method for generating test sequences for checking the conformance of a protocol implementation to its specification is described. A rural Chinese postman tour problem algorithm is used to determine a minimum-cost tour of the transition graph of a finite-state machine. It is shown that, when the unique input/output sequence (UIO) is used in place of the more cumbersome distinguishing sequence, both the controllability and observability problems of the protocol testing problem are addressed, providing ...
Tópico(s): Advanced Malware Detection Techniques
1991 - IEEE Communications Society | IEEE Transactions on Communications
Alfred V. Aho, Mahadevan Ganapathi, Steven Tjiang,
Compiler-component generators, such as lexical analyzer generators and parser generators, have long been used to facilitate the construction of compilers. A tree-manipulation language called twig has been developed to help construct efficient code generators. Twig transforms a tree-translation scheme into a code generator that combines a fast top-down tree-pattern matching algorithm with dynamic programming. Twig has been used to specify and construct code generators for several experimental compilers ...
Tópico(s): Algorithms and Data Compression
1989 - Association for Computing Machinery | ACM Transactions on Programming Languages and Systems
... G with maximal degree less than 5.[1] Alfred V. Aho, , John E. Hopcroft and , Jeffrey D. Ullman, The ...
Tópico(s): Optimization and Search Problems
1984 - Society for Industrial and Applied Mathematics | SIAM Journal on Computing
Alfred V. Aho, A.D. Wyner, Mihalis Yannakakis, Jeff Ullman,
Using a pair of finite-state automata to model the transmitter-receiver protocol in a data communications system, we derive lower bounds on the size of automata needed to achieve reliable communication across an error-prone channel. We also show that, at the cost of increasing the size of the automata, a transmission rate close to the theoretical maximum can be achieved.
Tópico(s): Cellular Automata and Applications
1982 - Elsevier BV | Computers & Mathematics with Applications
... shown that the problem is $NP$-complete.[1] Alfred V. Aho, , John E. Hopcroft and , Jeffrey D. Ullman, The ...
Tópico(s): graph theory and CDMA systems
1979 - Society for Industrial and Applied Mathematics | SIAM Journal on Computing
Alfred V. Aho, Jeffrey D. Ullman,
This paper considers the design of a system to answer partial-match queries from a file containing a collection of records, each record consisting of a sequence of fields. A partial-match query is a specification of values for zero or more fields of a record, and the answer to a query is a listing of all records in the file whose fields match the specified values. A design is considered in which the file is stored in a set of bins. A formula is derived for the optimal number of bits in a bin address ...
Tópico(s): Machine Learning and Algorithms
1979 - Association for Computing Machinery | ACM Transactions on Database Systems
Alfred V. Aho, Brian W. Kernighan, P. Weinberger,
Abstract This paper describes the design and implementation of awk , a programming language which searches a set of files for patterns, and performs specified actions upon records or fields of records which match the patterns. Awk makes common data selection and transformation operations easy to express; for example, is a complete awk program that prints all input lines whose length exceeds 72 characters. The program prints each input line with the first field replaced by its logarithm. The program ...
Tópico(s): Logic, programming, and type systems
1979 - Wiley | Software Practice and Experience
Alfred V. Aho, S. C. Johnson, Jeffrey D. Ullman,
This paper shows the problem of generating optimal code for expressions containing common subexpressions is computationally difficult, even for simple expressions and simple machines. Some heuristics for code generation are given and their worst-case behavior is analyzed. For one register machines, an optimal code generation algorithm is given whose time complexity is linear in the size of an expression and exponential only in the amount of sharing.
Tópico(s): semigroups and automata theory
1977 - Association for Computing Machinery | Journal of the ACM
Alfred V. Aho, M. R. Garey, F. K. Hwang,
Abstract A minimal rectilinear Steiner tree for a set A of points in the plane is a tree which interconnects A using horizontal and vertical lines of shortest possible total length. Such trees have potential application to wire layout for printed circuits. Unfortunately, at present no practical algorithm is known for constructing these trees in general. We present two algorithms, each requiring a number of operations proportional to only a low degree polynomial in the number of points to be interconnected, ...
Tópico(s): VLSI and Analog Circuit Testing
1977 - Wiley | Networks
This paper discusses algorithms which transform expression trees into code for register machines. A necessary and sufficient condition for optimality of such an algorithm is derived, which applies to a broad class of machines. A dynamic programming algorithm is then presented which produces optimal code for any machine in this class; this algorithm runs in time linearly proportional to the size of the input.
Tópico(s): Evolutionary Algorithms and Applications
1976 - Association for Computing Machinery | Journal of the ACM
Jeffrey D. Ullman, Alfred V. Aho, D. S. Hirschberg,
The problem of finding a longest common subsequence of two strings is discussed. This problem arises in data processing applications such as comparing two files and in genetic applications such as studying molecular evolution. The difficulty of computing a longest common subsequence of two strings is examined using the decision tree model of computation, in which vertices represent “equal - unequal” comparisons. It is shown that unless a bound on the total number of distinct symbols is assumed, every ...
Tópico(s): semigroups and automata theory
1976 - Association for Computing Machinery | Journal of the ACM
Alfred V. Aho, John E. Hopcroft, Jeffrey D. Ullman,
Trees in an n-node forest are merged according to instructions in a given sequence, while other instructions in the sequence ask for the lowest common ancestor of pairs of nodes. We show that any sequence of $O(n)$ such instructions can be processed "on-line" in $O(n\log n)$ steps on a random access computer. If we can accept our answer "off-line", that is, no answers need to be produced until the entire sequence of instructions has been seen, then we may perform the task in $O(n\alpha (n))$ steps, where $\ ...
Tópico(s): Error Correcting Code Techniques
1976 - Society for Industrial and Applied Mathematics | SIAM Journal on Computing
Alfred V. Aho, K. Steiglitz, Jeffrey D. Ullman,
We investigate the evaluation of an $(n - 1)$st degree polynomial at a sequence of n points. It is shown that such an evaluation reduces directly to a simple convolution if and only if the sequence of points is of the form $b, ba,ba^2 , \cdots ,ba^{n - 1} $ for complex numbers a and b (the so-called "chirp transform"). By more complex reductions we develop an $O(n\log n)$ evaluation algorithm for sequences of points of the form \[ b + c + d,\quad ba^2 + ca + d,\quad ba^4 + ca^2 + d, \cdots \] for complex numbers a, b, c and d. Finally ...
Tópico(s): Polynomial and algebraic computation
1975 - Society for Industrial and Applied Mathematics | SIAM Journal on Computing
Alfred V. Aho, Margaret J. Corasick,
This paper describes a simple, efficient algorithm to locate all occurrences of any of a finite number of keywords in a string of text. The algorithm consists of constructing a finite state pattern matching machine from the keywords and then using the pattern matching machine to process the text string in a single pass. Construction of the pattern matching machine takes time proportional to the sum of the lengths of the keywords. The number of state transitions made by the pattern matching machine ...
Tópico(s): DNA and Biological Computing
1975 - Association for Computing Machinery | Communications of the ACM
Alfred V. Aho, S. C. Johnson, Jeffrey D. Ullman,
Methods of describing the syntax of programming languages in ways that are more flexible and natural than conventional BNF descriptions are considered. These methods involve the use of ambiguous context-free grammars together with rules to resolve syntactic ambiguities. It is shown how efficient LR and LL parsers can be constructed directly from certain classes of these specifications.
Tópico(s): Logic, programming, and type systems
1975 - Association for Computing Machinery | Communications of the ACM
article Free Access Share on LR Parsing Authors: A. V. Aho Bell Laboratories, Murray Hill, New Jersey Bell Laboratories, Murray Hill, New JerseyView Profile , S. C. Johnson Bell Laboratories, Murray Hill, New Jersey Bell Laboratories, Murray Hill, New JerseyView Profile Authors Info & Claims ACM Computing SurveysVolume 6Issue 2June 1974 pp 99–124https://doi.org/10.1145/356628.356629Online:01 June 1974Publication History 82citation2,438DownloadsMetricsTotal Citations82Total Downloads2,438Last 12 Months70Last ...
Tópico(s): Algorithms and Data Compression
1974 - Association for Computing Machinery | ACM Computing Surveys
Alfred V. Aho, Jeffrey D. Ullman,
Related DatabasesWeb of Science You must be logged in with an active subscription to view this.Article DataHistorySubmitted: 05 June 1972Published online: 13 July 2006KeywordsParsing, compiling, parser optimization, LR(k) parsing, single productionsPublication DataISSN (print): 0097-5397ISSN (online): 1095-7111Publisher: Society for Industrial and Applied MathematicsCODEN: smjcat
Tópico(s): Natural Language Processing Techniques
1973 - Society for Industrial and Applied Mathematics | SIAM Journal on Computing