Abstract: Methods are disclosed for finding maximal matches in data strings and for finding matches in parameterized strings, that is, strings containing symbols from more than one alphabet in which the symbols from one of the alphabet are treated as parameters. In general, such maximal matches are found by creating a suffix tree representing the data string, generating lists for each node in the tree indicating the left contexts of all suffixes associated with that node and reporting matches for pairs of suffixes having different left contexts. One method of finding parameterized matches is to substitute a common symbol for the symbols of the alphabet representing the parameters before creating the suffix tree and then discarding matches found for which the actual parameters are not consistent.

Abstract: A system is disclosed for delivering audio and/or video signals to users in connection with the provision of interactive television services. Various sources of such signals are connected to a digital network, such as a packet network. Also connected to such network are control and application processors and interfaces to distribution arrangements such as cable television systems and telephone subscriber loops. Each user has a signal converter for receiving a digital signal from the distribution arrangement, converting such signal for viewing on a conventional television receiver and transmitting control packets to other elements of the system. The signal sources can include a data cache for storing recorded video and audio materials, a broadcast source for receiving broadcast signals, apparatus for composing multimedia signals from multiple sources and apparatus for running games.

Abstract: A handwritten test symbol, such as an alphabetic character, a word or a signature, written on a digitizing tablet is normalized by comparison with a model symbol to determine the transformation necessary to best fit the test symbol to the model symbol. Such transformation is then applied to normalize the test symbol. Shape information in the test symbol is preserved during such normalization. In accordance with one aspect of the invention, the model symbol is a line segment. In accordance with another aspect of the invention, the model symbol is an example of the symbol being normalized. Such normalization can be used as a preprocessing step in applications such as character recognition, text recognition or signature verification.

Abstract: Test vectors for a circuit containing both logic gates and memory blocks are evaluated by applying candidate test vectors to good and faulty versions of the circuit in a computer simulation. The functions of the gates and interconnections in the circuit are stored in memory and the operation of the good and faulty circuits is simulated concurrently. During the simulation, a memory record is created for storing the state of a circuit element in a faulty circuit if the fault is visible at the element. Such records are removed when no longer needed, which speeds up the simulation. A multiprocessor in a pipeline configuration is disclosed for performing the simulation. A first branch in the pipeline simulates the logic gates in the circuit; a second branch simulates the memory blocks.

Abstract: Interconnected cells, such as gates, are partitioned into blocks, such as integrated circuits, wherein the blocks have at least one constraint, such as number of pins available, on the placement of cells therein. The cells are initially assigned to blocks at random or in accordance with a previously-determined initial partition. A quality factor, such as the total number of pins on all blocks, is determined for the initial partition and cells are moved from block to block to form a new partition. The cell moves are selected so as not to violate the constraints and in accordance with the likelihood of improving the overall quality of the partition. Such partitioning is repeated and the overall quality factor is recalculated for each new partition. When the quality factor does not improve substantially from partition to partition, the last partition for which the quality factor improved is selected as the best.

Abstract: A method of using finite state machines (FSMs) is disclosed for controlling multiple processes in response to input signals. In an exemplary embodiment, such processes comprise facilities for providing interactive television services and multimedia signals for such services. The FSMs are arranged in a tree-like structure and communicate with each other by event messages of various types. Each FSM has multiple states and permitted state transitions. Transitions occur in response to event messages and/or input signals, and a transition can cause one or more event messages associated with such transition to be sent. At least one terminal FSM is associated with each of the multiple processes and controls that process. Status changes in each process can also cause state transitions in the FSMs. The FSMs are resident in the various processors controlling the multiple processes, which can be situated at different locations.

Abstract: The invention permits various types of background knowledge for a concept learning system to be represented in a single formal structure known as an antecedent description grammar. A user formulates background knowledge for a learning problem into such a grammar, which then becomes an input to a learning system, together with training data representing the concept to be learned. The learning system, constrained by the grammar, then uses the training data to generate a hypothesis for the concept to be learned. Such hypothesis is in the form of a set of logic clauses known as Horn clauses.

Abstract: A computer input device for use as a computer mouse or keyboard comprises a thin, insulating surface covering an array of electrodes. Such electrodes are arranged in a grid pattern and can be connected in columns and rows. Each column and row is connected to circuitry for measuring the capacitance seen by each column and row. The position of an object, such as a finger or handheld stylus, with respect to the array is determined from the centroid of such capacitance values, which is calculated in a microcontroller. For applications in which the input device is used as a mouse, the microcontroller forwards position change information to the computer. For applications in which the input device is used as a keyboard, the microcomputer identifies a key from the position of the touching object and forwards such key identity to the computer.

Abstract: Different components of television programs, such as the video and audio components or different time segments of the program, are assigned to different channels transmitted in the form of packetized digital information in at least one of the channels of a multi-channel cable television distribution system. A particular subscriber's converter is configured to receive a particular subset of program components by enabling the converter to receive the virtual channels carrying the components in such subset. An embodiment is disclosed in which different combinations of program segments are enabled for different subscribers. Another embodiment is disclosed in which the viewing of a program by multiple subscribers who begin viewing at different times is synchronized by using "filler" program segments having different lengths.

Abstract: The invention relates to a system for transmitting stored programs, such as movies and musical works, to customers via a distribution network, such as a cable television system. The programs are stored in compressed form in a program library, such as a tape cartridge library. On receipt of a request for a program, a request processor sends control messages causing a data block comprising the requested program to be read from the program library at high speed and stored in a large dynamic random access memory (DRAM) in a server. The server then sends the program from DRAM over the distribution system to a customer as a series of digital packets. Each instance of sending a program is managed by a separate command word. The customer can request such operations as "fast forward" by sending control messages that change pointers in the command word. Command words can be grouped to send multiple audio and/or video overlays simultaneously and linked to send program sequences.

Abstract: One or more channels in a multi-channel cable television distribution system is used for the transmission of interactive television (ITV) signals in the form of packetized digital information from the cable system headend to subscribers. A converter at each subscriber location is connected between the cable system and the subscriber's television receiver. Such converter contains a receiver for the ITV channels. Control packets in the ITV signals are addressed to individual converters to enable the receipt of one or more virtual channels by a converter. The converter decodes and expands the packetized digital information in such enabled channels and generates a conventional video signal, which is transmitted to the subscriber's television receiver on one of the channels used for the ITV signal from the headend, replacing the packetized digital information. The remaining channels from the cable system are forwarded to such television receiver unaltered.

Abstract: Signal distribution systems, such as interactive cable television systems, have a central server that communicates with remote terminals wherein the server assigns a specific address to each newly-connected terminal for control messages and polls. In the case of an interactive cable television system, such terminal is the set-top box or converter connected between the cable system and the television receiver. Periodically, the server broadcasts a control message containing a tentative address, and polls the tentative address. Upon receiving such a message, a newly-connected converter stores the tentative address and responds to the poll with an uplink message. After receiving the uplink message, the server inserts the tentative address in its polling list in accordance with the transmission delay measured from sending the poll to receiving the uplink message and selects a new tentative address to use in subsequent broadcast control messages.

Abstract: Capacitive proximity sensors are disclosed that can be fabricated in different shapes, sizes and materials used in a wide variety of applications. Each such sensor includes a sensing electrode and a guard electrode. The sensor electrode and guard electrode can be parallel conductors separated by an insulating layer, such as a double-sided circuit board shaped to suit the application. One such sensor is transparent for use in conjunction with an optical bar-code scanner. Another sensor is annular in shape for use in conjunction with a telephone transmitter. The sensing electrode and the guard electrode are driven in unison by an RF signal. The proximity of an object to the sensor is observed by detecting changes in the RF current flowing through the sensing electrode caused by the proximity of an object to the sensing electrode.

Abstract: An unknown handwritten symbol written on a digitizing tablet is compared with symbols in a predefined "alphabet" or library of model symbols and the closest match chosen. Recognition is independent of the size, position or orientation of the symbols. The alphabet can be any collection of symbols, such as alphanumeric characters, ideograms or words in cursive script and is created by writing at least one example of each symbol on the tablet. A sequence of samples of the pen position is recorded while a symbol is being written. The samples form a vector, which is then translated so that the centroid of the symbol lies at an origin. The comparison, which can easily be done in real time, involves calculating a correlation factor from scalar products of the vector for the unknown symbol and two versions of the vector for each model symbol and choosing the model symbol having the highest correlation factor.

Abstract: Slurry in a slurry polisher is ultrasonically agitated during polishing to dislodge embedded debris and grit from the polishing pad and thereby improve the uniformity of material removal, lengthen the life of the pad and avoid scratches and defects on the surface being polished. The method is particularly useful for applications in which slurry polishing is used for planarizing deposited layers on semiconductor wafers where non-uniformities caused by such embedded material can affect process yields. Apparatus is disclosed for applying ultrasonic energy to the slurry so that such energy is focussed on the pad.

Abstract: A cyclic analog-to-digital converter includes two arithmetic circuits and a single comparator. The output of each arithmetic circuit is connected to the input of the other arithmetic circuit. Each arithmetic circuit can modify the analog signal being converted in accordance with output signals from the comparator. Embodiments are disclosed in which the arithmetic circuits include switched capacitors and separate or shared operational amplifiers.

Abstract: A machine-based learning system receives inputs and proposes outputs using a network of connection weights to relate the inputs to the outputs. When a user affirms a proposed output, the system adjusts the connection weights to strengthen the relationship between elements of the inputs and that output. Learning occurs in the course of successive iterations as the connection weights adapt to relationships between semantically-significant input elements and related outputs. The system can be used to acquire language from inputs provided in the form of text or speech such that the connection weights adapt to semantically-significant words without need for defining word meanings. Such language acquisition contrasts with previous systems in which words are predefined.

Abstract: Disclosed is a three-dimensional circuit structure particularly useful in semiconductor memories. The circuit structure consists of a stack of modules mounted on a mother board with connectors between adjacent modules in the stack. The connectors mate with staggered and through terminals on the modules; the staggered terminals being used for circuits routed to destinations on specific modules and the through terminals for circuits routed to destinations on more than one module.

Abstract: Position indicating apparatus that allows position detection with windings provided on only one of two members and an output signal in which the position of one of the members relative to the other member is directly encoded in the phase of the output signal. A first member has a plurality of spaced ferromagnetic protuberances. A second member, movable with respect to the first member, contains at least first, second and third poles located in proximity to the protuberances and spans 360 spatial degrees. Each pole contains a winding with one terminal of each winding connected to a common point. The windings are driven at a fundamental carrier frequency with individual signals of equal amplitude but different temporal phases that span 360 temporal degrees. Circuit means detect the phase of the resulting carrier signal at the common point, which phase is linearly representative of position.

Abstract: A high-frequency wideband relaxation oscillator utilizing parasitic capacitances of the switching transistors as charging capacitors and capable of being fabricated in both CMOS and NMOS technology. When fabricated in NMOS technology the switching transistors are implemented as charge-enhancement devices and additional charge-depletion devices are utilized to counteract detrimental parasitic capacitances.