Abstract: Techniques for providing replicated files in a distributed system. A replicated file has a set of copies in components of the distributed system. Operations on the copies have the same semantics for the application processes accessing them as operations on a single copy of a file in a system where all processes execute on the same host. These semantics are achieved by means of a distributed synchronization system. Each replicated file has a read token and a write token. In order for an application process to perform an operation on a replicated file, the token required for the operation must be in the process's host and the process must have access to the token. Tokens are passed between hosts by token servers which respond to requests for tokens from application processes and from other token servers. The techniques are implemented using a library which replaces a standard I/O library, and may thus be employed without modification to hardware or the operating system.

Abstract: Apparatus for constructing a complex artifact out of primitive artifacts and other complex artifacts. The apparatus has a permanent knowledge base of primitive artifacts, previously-made complex artifacts, and rules defining how complex artifacts are made from primitive artifacts. All artifacts in the permanent knowledge base have been checked for consistency. Artifacts from the permanent knowledge base are displayed in a search area as directed graphs in which the artifacts are represented by nodes. A user may search the permanent knowledge base, and the directed graphs in the search area show the results of the search. To construct a new complex artifact or to add to a complex artifact under construction, the user selects nodes of the directed graphs which represent desired component artifacts. Information about the desired artifacts is copied from the permanent knowledge base to a working knowledge base and a directed graph of the contents of the working knowledge base is displayed in a work area.

Abstract: Apparatus and methods for training classifiers. The apparatus includes a degree of certainty classifier which classifies examples in categories and indicates a degree of certainty regarding the classification and an annotating classifier which receives classified examples with a low degree of certainty from the degree of certainty classifier and annotates them to indicate whether their classifications are correct. The annotated examples are then used to train another classifier. In one version of the invention, the other classifier is a new version of the degree of certainty classifier, and training continues until the degree of certainty classifier has satisfactory performance. The degree of certainty classifier of the embodiment is a probabilistic binary classifier which is trained using relevance feedback. The annotating classifier may include an interactive interface which permits a human user of the system to examine an example and indicate whether it was properly classified.

Abstract: A method for use in a high-speed virtual circuit digital network for resizing windows of virtual circuits in nodes of the network. The resizing of a virtual circuit's window is initiated by an input router at an edge of the digital network. When the input router determines that resizing is necessary, it sends a first congestion control message to the nodes through which the virtual circuit passes. If the message indicates a larger window, the node receiving the message determines what size window it can provide and sends the message with that window size on to the next node. An output router at the other edge of the digital network receives the message, sets the window size based on the message as altered by the nodes, and returns a second message with the final window size via the nodes. On receipt of the second message, the nodes alter their windows and the input router sends cells as permitted by the new window.

Abstract: Methods for determination of parts of speech of words in a text or other non-verbal record are extended to include so-called Viterbi optimization based on stored statistical data relating to actual usage and to include noun-phrase parsing. The part-of-speech tagging method optimizes the product of individual word lexical probabilities and normalized three-word contextual probabilities. Normalization involves dividing by the contained two-word contextual probabilities. The method for noun phrase parsing involves optimizing the choices of, typically non-recursive, noun phrases by considering all possible beginnings and endings thereof, preferably based on the output of the part-of-speech tagging method.

Abstract: A method of partial scan design for chip testing and a circuit produced in accordance with the method in which the selection of scan memory elements eliminates cycles in the circuit while the circuit is in a test mode. Cycles are defined as feedback paths from an output of a memory element to an input of the memory element. Cycle length is the number of memory elements in a feedback path. Experimental data suggests that test complexity grows exponentially with the cycle length. By eliminating cycles of desired lengths, the set of scan memory elements may be only a small fraction of the total memory elements of a circuit.

Abstract: A method of controlling congestion in a virtual circuit packet network. A initial packet buffer is assigned to each virtual circuit at each node into which incoming packets are stored and later removed for forward routing. If a larger buffer is desired for a virtual circuit to service a larger amount of data, then additional buffer space is dynamically allocated selectively to the virtual circuit on demand if each node has sufficient unallocated buffer space to fill the request. In one embodiment, the criterion for dynamic allocation is based on the amount of data buffered at the data source. In alternative embodiments, the criteria for dynamic allocation may be further based on the amount of data buffered at each node for a virtual circuit and the total amount of free buffer space at each node of a virtual circuit. Signaling protocols are disclosed whereby data sources and virtual circuit nodes maintain consistent information describing the buffer allocations at all times.

Abstract: A method and apparatus for determining a predominant angle of orientation of an image with respect to a reference angle. A file of picture elements is generated which depicts the image with respect to the reference angle. The picture elements are projected onto a plurality of contiguous segments of imaginary lines at selected angles across the file. Each imaginary line is perpendicular to its associated direction of projection. The number of picture elements that fall into the segments for each projection are counted. An enhancement function is applied to the segment counts of each projection. The projection that generates the largest value of the enhancement function defines the angle of orientation of the image. The position of a document scanner or the document itself may be rotated to compensate for the detected skew.