Showing papers on "String (computer science) published in 1977"

A fast string searching algorithm

Abstract: An algorithm is presented that searches for the location, “il” of the first occurrence of a character string, “pat,” in another string, “string.” During the search operation, the characters of pat are matched starting with the last character of pat. The information gained by starting the match at the end of the pattern often allows the algorithm to proceed in large jumps through the text being searched. Thus the algorithm has the unusual property that, in most cases, not all of the first i characters of string are inspected. The number of characters actually inspected (on the average) decreases as a function of the length of pat. For a random English pattern of length 5, the algorithm will typically inspect i/4 characters of string before finding a match at i. Furthermore, the algorithm has been implemented so that (on the average) fewer than i + patlen machine instructions are executed. These conclusions are supported with empirical evidence and a theoretical analysis of the average behavior of the algorithm. The worst case behavior of the algorithm is linear in i + patlen, assuming the availability of array space for tables linear in patlen plus the size of the alphabet.

Line‐Profile resist development simulation techniques

Abstract: The relative advantages and disadvantages of three different algorithms are compared for simulating the time evolution of two-dimensional line-edge profiles produced by a locally rate dependent surface etching phenomenon. Simulated profiles typical of optical projection printing and electron-beam and X-ray lithography of micron-sized lines in resist and etching of ion-implanted SiO2 are used as a basis of comparison. One of the algorithms is a cell-by-cell removal model used earlier by Neureuther and Dill. One of the newly developed algorithms employs ray tracing; it can be shown that the path followed by a point on a front between the developed and undeveloped regions can be calculated using ray-optic equations. The other new algorithm uses a string of points initially on the surface of the exposed resist. The points on the string advance perpendicular to the local direction of the string; with time the string of points moves down into the resist, replicating the action of a developer. We compare the computing cost, convenience, and accuracy of the algorithms.

On the Worst-Case Behavior of String-Searching Algorithms

Abstract: Any algorithm for finding a pattern of length k in a string of length n must examine at least $n - k + 1$ of the characters of the string in the worst case. By considering the pattern $00 \cdots 0$, we prove that this is the best possible result. Therefore there do not exist pattern matching algorithms whose worst-case behavior is “sublinear” in n (that is, linear with constant less than one), in contrast with the situation for average behavior (the Boyer-Moore algorithm is known to be sublinear on the average).

The Solution of Patterned String Problems By Birds

Abstract: 1. Three budgerigars quickly learned to pull to their cage a 15 cm long black string to which a small food container was attached. Then two strings of the same length but of different colour were offered, one of which was cosmected with a food container. One budgerigar learned successively with significant percentages of correct choices to pull the string with the container when both strings were arranged in one of 7 different patterns (Fig. 2 A-G). The bird mastered 2 of these arrangements spontaneously. Finally the budgerigar chose correctly in significant percentages of choices when 4 of these tasks were offered in predetermined irregular sequence in series of 30 trials. In these cases also the colours of the strings, the position of the correct string to the right or to the left, and the normal or the reflected arrangement changed in predetermined, irregular succession. These continuously changing situations always required different associative processes and new decisions. A second budgerigar mastered such tasks only when not more than string patterns were offered in irregular sequence. A third budgerigar learned to choose the correct string only when one of the simple string patterns A, B or C was offered in a series of trials. An Indian starling (Acridotheres tristis) and a jackdaw (Coloeus monedula) quickly learned to pull a string with a food container, but proved to be inappropriate for experiments with two strings because the handling of the strings in itself appeared rewarding to them. 2. The results of these experiments confirm that the brain achievements of birds are not inferior to those of mammals, although their forebrain lacks a cortex with several layers of neurons. They support the hypothesis that the specific configuration of forebrain regions is less important for more difficult brain achievements than the number and differentiation of neurons and the number of synapses.

Variable architecture digital computer

Abstract: A variable architecture digital computer to provide real-time control comations a for missile by executing efficient variable-length instructions optimized for such application by means of a microprogrammed processor and an instruction byte string concept.

A new proof of the linearity of the Boyer-Moore string searching algorithm

Abstract: The Boyer-Moore algorithm searches for all occurrences of a specified string, the pattern, in another string, the text. We study the combinatorial structure of periodic strings and use these results to derive a new proof of the linearity of the Boyer-Moore algorithm in the worst case. Our proof reduces the previously best known bound of $7n$ to $4n$, where n is the length of the text.

Stowable decorative lights

Abstract: A string of outdoor decorative lights is connected to a facer board on a building cave. A stowable embodiment of the invention provides hinged attachment to the facer board and means for securing the string in a display position or in a hidden position. Snap-in tabs hold the string in either position.

The 1976 modular acoustic processor(MAP)

Abstract: The modular acoustic processor (MAP), a complex experimental system for automatic derivation of phonemic string output for continuous speech, has stages dedicated to signal analysis, spectral classification, phonemic segmentation, phonemic (steady state) classification, phoneme boundary placement, dyadic (transitional) classification, and final phoneme string consolidation. This paper presents the concepts of and some details concerning these five stages. Results on a large body of continuous speech data, prepared by an automatic evaluation system, will also be presented.

Ornamental attachment for decorative string sets

Abstract: An ornamental structure for decorative string sets utilizing miniature and subminiature lamps is disclosed in which a seamless ornament is securely fastened about the lamp and wires to provide both a decorative and strengthening function.

Constraints on Structural Descriptions: Local Transformations

Abstract: It is very often more convenient and more meaningful to specify a set of structural descriptions analytically rather than generatively, i.e., by specifying a set of constraints each structured description in the set has to satisfy. Peters and Ritchie [7] have shown that if context-sensitive rules are used only for “analysis” then the string language of the set of trees is still context-free. In this paper, we have generalized this result by considering context-free rules constrained by Boolean combinations of proper analysis predicates and domination predicates. These rules, called "local transformations" not only make precise an informal and briefly discussed notion of Chomsky [2], but also, generalize it in an appropriate manner. It is shown that the Peters-Ritchie result can be generalized to local transformations. Linguistic relevance of this result has been also briefly discussed. Results in this paper are relevant to the following situation: Patterns of a class, say A, may be difficult to characteri...

An encoding method for multifield sorting and indexing

Abstract: Sequences of character strings with an order relation imposed between sequences are considered. An encoding scheme is described which produces a single, order-preserving string from a sequence of strings. The original sequence can be recovered from the encoded string, and one sequence of strings precedes another if and only if the encoding of the first precedes the encoding of the second. The strings may be variable length, without a maximum length restriction, and no symbols need be reserved for control purposes. Hence any symbol may occur in any string. The scheme is useful for multifield sorting, multifield indexing, and other applications where ordering on more than one field is important.

Peak Recognition in Waveforms

Abstract: A new system of peak component recognition and measurement in digitized waveforms is detailed. Two input parameters identify waveform context (scale and noise content), and a third specifies baseline tolerance (if applicable). The input waveform is preprocessed by a discrete linear piecewise approximation algorithm yielding a segmentation in endpoint/slope/constant format. Slope values are encoded as symbols of a string which is parsed by a syntax-directed finite-state automaton. One of three different machines and sets of semantic routines is chosen depending upon whether the waveform is baseline-free, unipolar, or bipolar. In the last case, the endpoint values relative to the baseline are encoded as symbols of a second string which modifies the action of the machine. An electrocardiogram is employed as an example waveform to demonstrate the bipolar algorithm, which runs with sufficient speed to allow real-time processing. A proposed on-line implementation of the system is outlined.

Decidability of a portion of the predicate calculus

Abstract: We show decidability of the existence of a model (a finite model) for sentences with the string of quantifiers ∀x(∃y1...yn), for a language with equality, one one-place function, predicates and constants.

Saving space in fast string-matching

Abstract: The string-matching problem is to find all instances (as contiguous substrings) of a “pattern” character string x in a longer “text" string ”. The naive algorithm, trying the pattern from scratch starting at each successive text position, requires only a fixed number of auxiliary storage locations but time proportional to $|x|\cdot|Y|$ (worst case). On the other hand, the fast algorithm of Knuth, Morris, and Pratt requires only time proportional to $|Y|$ but extra space proportional to $|x|$ (every case). Algorithms described in this paper reduce the extra space used by the Knuth–Morris–Pratt algorithm down to $O(\log |x|)$, and the time for the naive algorithm down to $O(|x|^\varepsilon |y|)$ for any fixed $\varepsilon > 0$. Also described are implementations on two-way multihead finite automata and multitape Turing machines.

Digital logic circuits for comparing ordered character strings of variable length

Abstract: Apparatus for automatically searching for a string of ordered characters stored on a magnetic tape wherein the string may be of selectable length employing a dynamic buffer register for storing the candidate strings of characters to be searched and a static/dynamic register for use in identifying the ordered reference string of characters used in performing the search, said candidate characters and reference characters being compared on a bit parallel character serial basis, means are provided to successively delay the relative positions of said reference characters and candidate characters in their respective register stages until a comparison indicates that the string of characters identified in the reference register have been located in the candidate register.

Transient-free working-set statistics

Abstract: Transient-free average working-set size and transient-free missing-page rate for a finite sample of a reference string are defined. Use of these statistics is appropriate if the contents of the working set at the start of the recorded string are unknown. If a certain stationarity condition holds, these statistics provide unbiased estimates of expected working-set sizes, missing-page probabilities, and interreference distance probabilities. Two other pairs of estimators are shown to be biased. Expressions for the transient-free statistics are obtained in terms of interval statistics. Several methods of computation are discussed, the usefulness of each depending on length of the sample, number of distinct references, and the amount of main storage available to the computer performing the calculations. In particular, methods are described for handling long strings containing many distinct page names.

Lamp lead to wire attachment for integral string sets

Abstract: A string set construction is disclosed in which the leads from a wire lamp are mechanically joined to wire in the power cord by a plastic sandwich including the insulation on the power cord.

Two-Way Finite Automata

Abstract: Two-way finite automata are similar to the machines we have been studying, except that they can read the input string in either direction. We think of them as having a read head, which can move left or right over the input string. Like ordinary finite automata, they have a finite set Q of states and can be either deterministic (2DFA) or nondeterministic (2NFA).

String instrument tuning system

Abstract: A musical instrument tuning system disposed and displayed upon a string instrument. The tuning system includes a first indicator displayed upon the surface of the string generally having three indicia zones representing a pitch alignment zone, a string tension load warning zone, and a zone indicating that the string is below pitch. The first indicator may take the form of a coating applied to the external surface of the string providing a plurality of visually discernable bands. A second indicator is displayed upon the instrument to provide a visual reference for the string markings. Rotatable displacement of a peg to which the string is fixedly secured provides for linear displacement of the bands with respect to the second indicator. Thus, rotation of the peg resulting in alignment of the tension load warning zone with the second indicator alerts the user that the string may rupture upon the addition of further tension. Opposite rotation of the peg resulting in alignment of the low pitch zone marking on the string with the second indicator demonstrates to the user that the string is tuned below pitch.

Nephis: A nested‐phrase indexing system

Abstract: NEPHIS is a system of computer-aided permuted subject indexing designed to be an easy as possible for the indexer, for the programmer, and for the user of the index. The indexer needs to learn only four commands in order to be able to construct any input string. Yet the permutations produced are elegant and browsable, while providing a complete description of even quite complicated subjects. The program is cheap to run, requiring only an input file and an output file and 1K of core.

Single string retrievable well packers

Abstract: A single string well packer having a pair of unitary tubular gripping members is disclosed which can be set by wireline, hydraulic pressure, or mechanically or tubing string.

Pattern recognition device

Abstract: PURPOSE:To obtain a dictionary exclusive use for each user b using an individual pattern dictionary for a pattern recognition to an input pattern, applying language processing as a post-processing and using a personal dictionary for the purpose. CONSTITUTION:An input pattern string 70a (string of character, voice of other pattern) is inputted to a pattern observing section 71, a pattern string 71a converted into an electric signal, the pattern is segmented at each unit pattern by a segmentation section 72 and the pattern is converted into unit pattern strings 72a. Each unit pattern is inputted to a pattern recognition section 73, and after the similarity with each standard pattern 74a belonging to a personal pattern dictionary 74 for pattern recognition is evaluated, >= one candidate category string 73a is outputted. A language processing section 75 outputs a category string 74a besed on the language processing between the content 76a belonging to the personal dictionary 76 for language processing and the category string 73. As the language processing, word collation, paragraph processing, syntax analysis and significance analysis are used.

Several results in program size complexity

Abstract: Intuitively, the program size complexity of a binary string measures the amount of information in the string. Researchers have formalized this notion in a number of different ways. Here, we demonstrate similarities between some of these formulations. We also investigate in some detail the properties of Kolmogorov's complexity measure.

Transforming medical records into a structured data base

Abstract: The N.Y.U. Linguistic String Project (LSP) is presently engaged in applying its programs for natural language processing to medical records. The programs transform the free narrative input into a structured data base suitable for automatic information processing, such as question answering, editing of records, or statistical summaries of the data. In order to determine the appropriate structures for a given type of material we first perform a manual linguistic analysis on a sample of the texts prior to processing. From this we obtain a set of word classes and a tabular form (called an information format) for this type of material. We then apply the series of processing programs to the sentences of the texts. Each sentence is parsed with the Linguistic String Parser English grammar in order to obtain its grammatical structure; then certain standard English transformations are applied to regularize the grammatical form of the sentence. Finally a set of "formatting transformations" map the words of the sentence into the slots of the information format, or table, for this material in such a way that the sentence is reconstructible up to paraphrase from its representation in the table.

On the time required to construct a simple linear order

Abstract: Pairs of digits or two-syllable words were presented visually for subjects to study as long as necessary in order to construct a single string reflecting the ordering inherent in the pairs. For example, given 75, 27, 58, the subject was to produce 2758. The time spent studying individual pairs was shown to reflect a set of five constructive processes identified in a theory proposed by Foos, Smith, Sabol, and Mynatt (1976) to account for errors in constructing the correct order. In addition, the results indicate that the time required to determine that a pair contains no elements in common with previously presented pairs is greater for two-syllable words than for digits, suggesting that an exhaustive search through short-term storage is occurring.

The vector string descriptor as a tool in the analysis of cellular automata systems

Abstract: A major impediment in the application of cellular spaces to the modeling of biological phenomena and other physical processes has been the lack of tools which relate global to local behavior. In this paper, the vector string descriptor is introduced as a tool for the analysis of cellular spaces similar to those studied by S. Ulam. With such a tool, it is quite straightforward to show the existence of global properties which would otherwise be very difficult to prove. For example, a conjecture by Ulam concerning the density of cells in a “growth” pattern is shown to be true. We also show that a self-reproduction process occurs which allows regeneration of specific patterns from “cuttings” of those patterns.

The Contextsensitivity Bounds of Contextsensitive Grammars and Languages

Abstract: In this paper we study the derivational complexity of contextsensitive grammars and languages by placing bounds on their contextsensitivity The contextsensitivity of a grammar is defined on its derivations, and it is determined by the maximal length of the strings of ancestors of any symbol occurring at any position of the derived strings A total recursive function f bounds the (right-) contextsensitivity function of grammar G, if for every terminal string x of length n generated by G there is a (right-canonical) derivation from S to x in G whose contextsensitivity is less than or equal to f(n)

Syntactic error correction in programming languages.

Abstract: A technique for syntactic error correction, called pattern mapping, is developed. A pattern is used to describe how to map or change one string into another. Using a preconstructed list of patterns, for each detected error, the first pattern with successful mapping is found and a correction is made based on this pattern.