Showing papers on "String (computer science) published in 1979"

Avoidable patterns in strings of symbols

Abstract: A word is just a finite string of letters. The word Wavoids the word U provided no substitution instance of Uis a subword of W. W is avoidable if on some finite alpha-bet there is an infinite collection of words each of whichavoids W. W is A th power-free if W avoids x , where x isa letter. We develope the theory of those endomorphismsof free semigroups which preserve A th power-freeness andemploy this theory to investigate &th power-free words.We go on to prove that every Mh power-free word on nletters is a subword of a maximal word of the same kind.Next we examine avoidable words in general and provethat all words of length at least 2

Awk — a pattern scanning and processing language

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 prints all lines in which the first field is different from the first field of the previous line. Patterns may include boolean combinations of regular expressions and of relational operators on strings, numbers, fields, variables, and array elements. Actions may include: the same matching constructions as in patterns; arithmetic and string expressions and assignments; if-else, while, and for statements; formatted output; and multiple output streams.

A Hierarchical Syntactic Shape Analyzer

Abstract: In many cases a picture is described in terms of various plane objects and their shape. This paper describes a parser whose input is a piecewise linear encoding of a contour and whose output is a string of high-level descriptions: arcs, corners, protrusions, intrusions, etc. Such a representation can be used not only for description but also for recognition. Previous syntactic techniques for contour description have often used high-level languages for the description of contours. This has been necessary in order to guarantee contour closure and eliminate the noise. In the present approach the numerical preprocessing of the contour removes most of the noise and also produces the answers to certain simple questions about its shape. Therefore, simpler grammars can be used for the contour description. Examples of descriptions of contours are given for handwritten numerals, white blood cells, and printed wiring circuit boards.

Method and means for arithmetic coding utilizing a reduced number of operations

Abstract: A method and means of arithmetic coding of conditional binary sources permitting instantaneous decoding and minimizing the number of encoding operations per iteration. A single shift and subtract operation for each encoding cycle can be achieved if an integer valued parameter representative of a probability interval embracing each source symbol relative frequency is used for string encoding and control. If the symbol being encoded is the most probable, then nothing is added to the arithmetic code string. However, an internal variable is updated by replacing it with an augend amount. If the updated internal variable has a leading zero, then both it and the code string are shifted left by one position. If the symbol being encoded is the least probable, then a computed augend is added to the code string and the code string is shifted by an amount equal to the integer valued parameter.

Common Properties of Some Multiattribute File Systems

Abstract: This paper results from an attempt to unify several different file system design theories. We define a term "partial match pattern" and show that in order to produce file systems optimal with respect to partial match patterns, both the multikey hashing (MKH) method [16] and the multidimensional directory (MDD) method [11] must be in such a form that the number of subdivisions is the same for all domains of keys. We show the conditions for the string homomorphism hashing (SHH) method [15], the MKH method, and the MDD method to be equivalent to one another. We define the so-called Cartesian product files and show that if all records are present, the records in a Cartesian product file form a shortest spanning path in which the Hamming distance between every pair of consecutive records is 1. Thus the SHH method, the MKH method, the MDD method, and the multikey sorting (MKS) method [10] are linked together. Finally, we show that for both partial and best match queries, the file systems exhibit a common characteristic: similar records are grouped together.

Electric string instrument

Abstract: The guitar has a novel feedback arrangement for sustaining the sound generated from the strings and including a pickup associated with each string and a corresponding driver intercoupled with the pickup in a feedback loop that also includes a gain-controlled amplifier. The amplifiers are controlled in common from a variable control means. The pickups, drivers and associated electronics are all commonly mounted from the bridge. In an alternate embodiment of the invention there is provided an improved sustain technique that provides a more natural sustain characteristic, employing a parametric type of excitation. This embodiment may comprise a pickup, amplifier and tensioning member responsive to the output of the amplifier for sustaining string vibration by causing longitudinal string displacement by means of the tensioning member. In a similar embodiment the string tension may be held constant and the string length varied instead.

Method and means for carry-over control in the high order to low order pairwise combining of digits of a decodable set of relatively shifted finite number strings

Abstract: Carry-over control in strings resulting from the high to low order combining of two binary number strings is obtained through the insertion of a control character within the resultant string after detecting a run of consecutive 1's. Upon subsequent accessing and decomposition of the resultant string, the control character causes string decomposition to operate for a number of cycles in a carry correction mode. If the control character indicates that a carry has rippled through the n lesser significant positions of the resultant string, then upon decomposition, those "n" consecutive 1's are changed to 0's, and a 1 is added to the least significant position in the string preceding the control character. If the control character indicates no carry occurrence, then it is merely deleted from the string. The control of carries in this manner permits the generation of arithmetic string compression code sequences in an instantaneous FIFO pattern with only a modest reduction of compression efficiency. Relatedly, the encoder and carry suppressor is shown in FIG. 2, while the carry corrector and decoder is shown in FIG. 4.

Adjustable nut for stringed musical instrument

Abstract: A device for use with a musical instrument to facilitate independent adjustment of the spatial relationship between fretboard and each string.

Method and apparatus for character reading

Abstract: A method for character reading requiring no character segmentation, which method effects required character recognition by the steps of subjecting a given string of character patterns to continuous scanning to produce either a local feature vector at each of the intersections of rows and columns of character patterns or a global feature vector for each of the columns formed in consequence of the scanning, linearly consolidating either or both of the feature vectors to obtain a lower dimensional vector in new feature axes and continuously matching the vectors with the standard ones set in advance.

Stringed musical instrument with electrical feedback

Abstract: A stringed instrument with feedback is formed from a string of 30 to 100 feet in length stretched taught and having pickup and driving transducers located at respective opposite ends of the string. An electronic processing system receives a signal from the pickup transducer and feeds it to the driving transducer. Each transducer comprises a pair of transducers oriented at right angles to each other and to the string, thus allowing for two independent signal channels to exist in the system.

Means for controlling special musical effects

Abstract: A means for controlling special musical effects in synchronism with picking a string of a stringed musical instrument by a pick. More specifically, the disclosure describes a means whereby a signal generated as a result of a pick breaking contact with a string of the stringed instrument initiates a special musical effect. The special musical effect may alter the output of a pick-up generated by vibration of the strings, or may be independent of string vibration and merely initiated by the pick breaking contact with the string. Also, disclosed is a pick having a conductive portion and a nonconductive portion so that picking a string by the conductive portion initiates a special musical effect and picking the string by the nonconductive portion results in the instrument operating in a conventional manner without the special musical effect. A pick is also disclosed having two separate conductive portions and a nonconductive portion so that different effects can be achieved in accordance with which portion of the pick is used to pick the strings. Also disclosed is a pick means which can activate a special musical effect even though the strings of the stringed instrument are not conductive.

A String Model Etching Algorithm

Abstract: : The basic algorithm and software implementation of a string model for simulation of surface etching are presented. The algorithm models the time evolution of a line edge profile by advancing nodes or points on a piecewise linear curve representing the profile. The specific formulas for the direction and rate of advance, insertion and deletion of points and deletion of loops are shown. Complete software documentation in the form of parameter definitions and a listing of the FORTRAN code for a CDC 6400 machine are included.

On the Complexity of General Context-Free Language Parsing and Recognition (Extended Abstract)

Abstract: Several results on the computational complexity of general context-free language parsing and recognition are given. In particular we show that parsing strings of length n is harder than recognizing such strings by a factor of only 0(log n), at most. The same is true for linear and/or unambiguous context-free languages. We also show that the time to multiply \(\sqrt n \times \sqrt n\) Boolean Matrices is a lower bound on the time to recognize all prefixes of a string (or do on-line recognition), which in turn is a lower bound on the time to generate a particular convenient representation of all parses of a string (in an ambiguous grammar). Thus these problems are solvable in linear time only if n×n Boolean matrix multiplication can be done in 0(n2).

Apparatus for carrying first and second weight loads of a tubing string

Abstract: An apparatus is provided which is connectable on a tubing string extendible into a subterranean well. The apparatus is selectively separatable whereby the tubing string may be parted. The apparatus comprises first means selectively retrievable from the apparatus for carrying across the apparatus a first weight load defined through the tubing string below the apparatus. Second weight load carrying means are provided for carrying across the apparatus a second weight load defined through the tubing string below the apparatus, the second weight load being less than the first weight load. The second means are activatable to separate the apparatus and the tubing string when the second weight load is exceeded.

Electronic tuning aid with digital readout

Abstract: An electronic tuning aid with luminous digital readout adapted by structural and functional features to be operational by placement on the body of string and musical instruments such as the guitar. A shiftable photoelectric probe constituting a unitized component of the device is of an optical character uniquely sensitive to both damped and undamped string vibration of slight amplitude to activate included solid-state counting and translating components affording a numeric display of the frequency of individually selected strings. Steel strings are automatically driven in sustained vibration by an electromagnetic drive system affecting only the selected string and timed by such string in a feedback circuit with the probe.

Kite string wrapper

Abstract: A kite string reel device, including a reel or spool rotated manually by means of a crank handle, the reel being supported inside a box-like frame or housing, and the reel, in one design, being adjustable for handling different lengths of string, by having an adjustable sized hub.

Picture shape converter

Abstract: PURPOSE:To attain picture-shape conversion as a substitute for floating-point arithmetic easily at a high speed, by using a simple address converter unit with a curve pattern generator combined. CONSTITUTION:In registers 601 to 610, numbers (m) and (n), and X and Y addresses of four points P11, Pm1, Pmn, and P1n are set. Straight-line generators 619 to 622 are used to generate a string of the (n)-number points P11, P12, P13..., Pij, ...P1n approximating to straight line P11P1n and a string of the (n)-unmber points Pm1, Pm2..., Pmj, ..., ..., Pmn approximating to straight line Pm1Pmn and they are set to registers 611 to 614. Straight-line generators 623 and 624 are also used to generate a string of the (m)-number points P1j, P2j...Pij,..., Pmj approximating to straight line PljPmj. Address update circuit 625 generates address (i,j) for picture 2, and a value at point Pij of picture 1 is read out by memory access circuit 7 and stored as the (i,j)-the element of picture 2. This operation is executed as to all (i,j).

A constant separation control law for use in automated guideway transit

Abstract: This report describes a control method for operating a string of vehicles under a constant separation policy which does not result in string instability. Each vehicle, rather than only looking at the preceding vehicle, also receives a velocity command which is common to all vehicles. The feedback controller is split into two parts, one to control based on vehicle separation error and the other to control based on velocity error. By properly apportioning the feedback gain between these two paths, string instability is overcome. A simulation of a five vehicle string demonstrates the validity of the technique.

A bubble string comparator for information processing

Abstract: A new magnetic bubble device is proposed: the bubble string comparator. It performs the sorting of couples of data without any logical control, depending only on the nature of the couples themselves. By means of an external control the bubble string comparator can also operate as a standard binary switch, either in bypass mode or in cross-over mode.

Digital communication system with high data throughput in a meshed network

Abstract: The invention relates to systems for digital communication by bit- packets, across meshed networks. The address message for each packet consists of a sequence of bit strings, each characteristic of one of the communication nodes traversed, and arranged in the order of traversing the nodes whose devices for routing (A1) the packets include means of decoding (16) then of deleting the leader from the bit string received, using a breaker (12) inserted into the circuit of a reception channel R1 and controlled by a counter (17) of the length of this string. Application to the joint transmission of telephone and data signals.

Content-addressed text search apparatus for typewriters

Abstract: A search system is provided that locates a reference point in a string of text-representative codes based on comparisons with an operator keyboarded text string (the address string). Such comparisons are automatically modified, however, to equate certain codes and code patterns that present an ambiguity to the operator in establishing the address string, e.g. a tab operation and a series of space operations may have the same apparent result for printing but are stored as different codes. By so expanding the acceptable "matching" code patterns selectively with respect to the codes presented for comparison, the likelihood of operator success in identifying a desired text location is increased significantly.

Method and apparatus for knotting automatically mouths of flexible packagings

Abstract: A method and apparatus for knotting flexible packages especially suited to knotting filled sausage casings, in which a loop of string is positioned adjacent to the area of the package to be knotted, and one end of the loop is drawn around the package and through the loop itself, and then pulled tightly, thus knotting the string around the package.

Method of monitoring a continuously advancing string material

Abstract: A method of monitoring continuously advancing string material (1) of the kind comprising a continuous alternating succession of string sections, for example a cigarette filter string, of different material and/or structural configuration with regard to cutting the string (1) into identical plugs (7) for checking and correcting the position of each cut. Prior to being cut the string (1) is scanned by a sensor unit (4) which detects the beginning and end of each string section. A device associated with the cutting device (5) generates an output signal to indicate the moment when the string (1) is cut. Between this output signal and the moment at which the sensor unit (4) issues a signal corresponding to the end of the string section to be cut, a measured value is obtained which is independent of the feed into of the string (1) and which is proportioned to the length of the string section between the two signals. This measured value is then compared with a reference value and the operative stroke of the cutting device (5) is adjusted when a certain number of successive measured values deviate in the same direction from the reference value.

Estimating the Mean of a Correlated Binary Sequence with an Application to Discrete Event Simulation

Abstract: : This paper discusses a procedure for interval estimation of the mean theta of a correlated binary (0,1) sequence. The method assumes that the sequence is strictly stationary and that a particular string of m binary digits is a recurrent event in the sequence, where mor = to 1 is unknown. Of the 2 m squared choices for the possible recurrent events, the strings of all zeros and of all ones are examined.

Maximal derivations for probabilistic strings in stochastic languages

Abstract: A probabilistic string is a sequence of probability vectors. Each vector specifies a probability distribution over the possible symbols at its location in the string. In a probabilistic grammar a probability is assigned to every derivation. Given a probabilistic string and a probabilistic grammar the concept of a maximal derivation is defined. Algorithms for finding the maximal derivation for probabilistic finite state and linear grammars are given. The case where a waveform can be segmented into several possible probabilistic strings is also considered.