Showing papers on "String (computer science) published in 1972"
TL;DR: An algorithm is presented that will parse any input string to completion finding the fewest possible number of errors on a random access computer.
Abstract: We assume three types of syntax errors can debase the sentences of a language generated by a context-free grammar: the replacement of a symbol by an incorrect symbol, the insertion of an extraneous symbol, or the deletion of a symbol. We present an algorithm that will parse any input string to completion finding the fewest possible number of errors. On a random access computer the algorithm requires time proportional to the cube of the length of the input.
239 citations
TL;DR: In this paper, a history of the problem is given, including superperiod data for quadratic and cubic nonlinear terms, together with a computation for a prime number of particles in the string extension to a circular array is discussed.
63 citations
TL;DR: An automatic car-following system based on optimal control theory is developed for a variety of cost functionals and the resultant system is simulated on an analog computer.
Abstract: An automatic car-following system based on optimal control theory is developed for a variety of cost functionals and the resultant system is simulated on an analog computer. Position and velocity response as well as local and asymptotic stability characteristics of a string of vehicles are examined. String behavior when a vehicle leaves or enters the string is also considered. By proper choice of the cost functional, it is shown that a car-following system can be obtained which meets the outlined objectives. Various forms of cost functionals are investigated in order to determine their effect on system performance.
20 citations
18 citations
TL;DR: Equational representations of String Adjunct Grammars, LAG's with null symbols, and some special cases of LAGs are studied.
Abstract: In this paper, we continue the study of String Adjunct Grammars (AG) introduced in Joshi et al. (1972). In particular, equational representations of LAG's, LAG's with null symbols, and some special cases of LAG's are studied. Linguistic relevance of these grammars is also discussed in some detail.
17 citations
TL;DR: Properties of the moments of string and derivation lengths of stochastic context-free grammars are examined and it is shown that, if the first moment exists and is finite, then all higher moments are finite.
15 citations
01 Jan 1972
TL;DR: This paper focuses on the middle two of the DIAM levels - the String Structure and the Encoding Models.
Abstract: The Data Independent Accessing Model (DIAM) Project of the Information Sciences Department of IBM Research is directed towards developing an architectural basis for an advanced data base system - a data base system which, in addition to providing advanced functional capabilities and a new level of data independence, is not limited either in the access paths which can be declared (in order to support the user-specified information collections) or in the encodings which are possible for those access paths.We have already been presented with a general overview of the basic system (1). In that overview, DIAM was seen to be composed of 4 basic levels of description:the Entity Set Modelthe String Structure Modelthe Encoding Modelthe Physical Device Model.In this paper we shall concentrate on the middle two of these levels - the String Structure and the Encoding Models.
12 citations
TL;DR: An efficient method for suboptimal feedback control of spacing and velocity errors within a string of vehicles is presented and the performance compares favorably with the performance of the optimal system.
10 citations
Patent•
12 Jul 1972
TL;DR: In this article, a system for marine search and salvage operation wherein sensing and grappling means are suspended by a pipe string from a surface vessel is described, and the results show that the system performs well.
Abstract: A system for marine search and salvage operation wherein sensing and grappling means are suspended by a pipe string from a surface vessel.
9 citations
TL;DR: It is proved that under certain conditions imposed on the rules of the grammar the computing time required by the modified algorithm is bounded linearly by the length of the input string.
8 citations
PARC1
TL;DR: An isolated word recognition system that uses character string encoding is described that has achieved 98% correct recognition scores on limited vocabularies (20-54 words).
Abstract: An isolated word recognition system that uses character string encoding is described that has achieved 98% correct recognition scores on limited vocabularies (20-54 words). Speaker normalization, word segmentation, and learning paradigms have been incorporated. Audio input passes through a 6-channel octave band pass filter bank. The output of each channel is time integrated for 10 ms, and log mapped. An utterance is represented by a succession of points (a new point is generated every 10 ms) in the 6- dimensional space defined by the 6 octave bands. Reference points are scattered throughout the space. Each time interval is assigned the label of the nearest reference point. We call the resulting string of labels a "character string". Encoding an utterance into a character string may proceed with an arbitrary degree of precision, greater resolution resulting from the use of more reference points. Only 24 reference points are needed to achieve 98% correct recognition scores for 54 words in near real time. String generation techniques are explored. Several learning schemes based on character strings are described. Finally, experiments with a software classifier that uses "deformable templates" based on character strings are presented.
Patent•
10 Oct 1972
TL;DR: A machine for automatically binding or tying a package delivered onto a table wherein the advancing speed as well as the slackening speed of the string, strap or the like with which to bind or tie the package are suitably controlled is described in this article.
Abstract: A machine for automatically binding or tying a package delivered onto a table wherein the advancing speed as well as the slackening speed of the string, strap or the like with which to bind or tie the package are suitably controlled. After one package has been bound, the cut end of the string is grasped by grasping structure so as to ready the string for the next binding operation.
TL;DR: A block is a three-dimensional aggregate of characters in the form of a right parallelepiped, best thought of as a threedimensional extension to a string as mentioned in this paper, which can be printed, concatenated in any of three dimensions, and merged on the basis of program-defined connection points.
Abstract: A new datatype, called a block, has been implemented for SNOBOL4. A block is a three-dimensional aggregate of characters in the form of a right parallelepiped, best thought of as a three-dimensional extension to a string. (The third dimension is used for overstriking.) Blocks may be printed, concatenated in any of three dimensions, and merged on the basis of program-defined connection points. Some blocks adapt in size and shape to their environment.Blocks and their operations are mainly used for composing printable output. A variety of graphical problems (including flowcharting, bargraphs, logic diagrams, mathematical-equation formation, and text justification and preparation) have been programmed on a printer in what appears to be an easy and natural way. In addition to these somewhat specialized applications, blocks appear to be a good general purpose device-independent output formation mechanism especially suitable for nonnumerical work.The concept of a block is largely language independent. That is, blocks require little in the way of specialized syntax and could readily be absorbed into the external structure of most programming languages.
01 Aug 1972
14 Jun 1972
TL;DR: In this article, it was shown that a grammar such that in each noncontext-free rule of G, the right side contains a string of terminals longer than any terminal string appearing between two nonterminals in the left side is context-free.
Abstract: If G is a grammar such that in each noncontext-free rule of G, the right side contains a string of terminals longer than any terminal string appearing between two nonterminals in the left side; then the language generated by G is context-free Six previous results follow as simple corollaries of this theorem
TL;DR: In this article, a four-digit string was heard by a speaker and saw a two-digit probe immediately after each of the four digits and every possible combination of two digits taken from the string, as well as each member of the string combined with some digit from the negative set was tested.
Abstract: Ss heard four-digit strings and saw a two-digit probe immediately after each. Every possible combination of two digits taken from the string, as well as each member of the string combined with some digit from the negative set was tested. Reaction times for verifying that both probe digits occurred in the string reveal that Ss grouped the members of the string into two ordered pairs. This result argues that the structure Ss might assign to so-called random strings must be considered when discussing scanning strategies. Structural explanations of two common patterns of reaction times are presented.
TL;DR: The permutations of the input string achievable by an algorithm which uses a single pushdown stack and M random access storage locations are characterized, and the characterization is used to show that no such algorithm can translate arithmetic expressions from infix to prefix.
Abstract: The permutations of the input string achievable by an algorithm which uses a single pushdown stack and M random access storage locations are characterized, and the characterization is used to show that no such algorithm can translate arithmetic expressions from infix to prefix.
Patent•
25 Jul 1972TL;DR: In this article, selected write circuits in a serial string of enhanced propagation pulse write circuits are activated by modulating the magnetic bias fields in the local vicinity of the selected circuits a sufficient amount to cause only the selected circuit to respond to enhanced propagation pulses, which are normally of insufficient amplitude to activate any of the write circuits.
Abstract: Selected write circuits in a serial string of enhanced propagation pulse write circuits are activated by modulating the magnetic bias fields in the local vicinity of the selected circuits a sufficient amount to cause only the selected circuits to respond to enhanced propagation pulses, which are normally of insufficient amplitude to activate any of the write circuits.
01 Sep 1972
TL;DR: Character string handling in the programing languages SNOBOL 4, TRAC, APL, and PL/I are compared and examples of string handling problems coded in the four languages are provided.
Abstract: Character string handling in the programing languages SNOBOL 4, TRAC, APL, and PL/I are compared. The first two of these are representatives of string processing languages, while the latter two represent general purpose programing languages. A description of each language is given and examples of string handling problems coded in the four languages are provided. Finally, the languages are compared on the basis of their string handling abilities rather than on the basis of implementation-dependent characteristics. (Author) TILN1ED FROM BEST AVAILABLE COPY University of North Carolina at Chapel Hill Department of Computer Scienee A COMPARISON OF STRING HANDLING IN FOgR PROGRAMMING LANGUAGES
IBM1
TL;DR: The well-known lower bound of log2n! on the number of comparisons required to sort n items is extended to cover algorithms, such as replacement selection, which produce a sorted string whose length is a random variable.
Abstract: The well-known lower bound of log2 n! on the number of comparisons required to sort n items is extended to cover algorithms, such as replacement selection, which produce a sorted string whose length is a random variable. The case of algorithms which produce several strings is also discussed and these results are then applied to obtain an upper bound on the length of strings produced by a class of string generation algorithms.
TL;DR: In this paper, a mathematical model for a vibrating non-linear string is constructed and an optimal control problem with a quadratic cost criterion is posed and necessary conditions for optimal controls are derived.
Abstract: A mathematical model for a vibrating non-linear string is constructed. An optimal control problem with a quadratic cost criterion is posed and necessary conditions for optimal controls are derived.
DOI•
01 Jan 1972
TL;DR: The results showed that under these conditions Ss are able to engage in a fast self-terminating search, and demonstrated that a self- terminating model, which assumes that the S starts his scan at the middle position of the probe array, proceeding in aSelf-Terminating fashion to either side, fits the major aspects of the data.
Abstract: Latency of S's response was measured in a task involving recognition memory for short lists of numbers or letters. Subjects saw a list of one to five items presented simultaneously, followed by a string of identical probe items, matched spatially to the locations of the memory set. The S indicated whether the probe item was the same as an item in the memory set. The results showed that under these conditions Ss are able to engage in a fast self-terminating search. The second experiment demonstrated that a self-terminating model, which assumes that the S starts his scan at the middle position of the probe array, proceeding in a self-terminating fashion to either side, fits the major aspects of the data.
TL;DR: This paper discusses a solution to the problem in which an inexpensive interface sets the test conditions locally, so that a long string of data can be transmitted to the computer when the telephone line is open.
Abstract: Computer-aided testing is usually performed with a dedicated computer, typically adding a five-digit number to the cost of the test equipment. In such systems the computer sets the test conditions and then records the test results from digital meters. This approach can lead to intolerably slow measurements when the dedicated computer is replaced by a remote time-shared computer. This paper discusses a solution to the problem in which an inexpensive interface (under 1000 dollars) sets the test conditions locally, so that a long string of data can be transmitted to the computer when the telephone line is open. A typical application is the evaluation of high-power microwave transistors, using a standard network analyzer. Connected to a Teletype, the system covers up to 40 frequency points in about 20 s, and displays the calculated and corrected S-parameters within another 20 s. If connected to the computer line through a 1200 Bd line, the system is speeded up by a factor of approximately 10.