Abstract: A wait-free implementation of a concurrent data object is one that guarantees that any process can complete any operation in a finite number of steps, regardless of the execution speeds of the other processes. The problem of constructing a wait-free implementation of one data object from another lies at the heart of much recent work in concurrent algorithms, concurrent data structures, and multiprocessor architectures. First, we introduce a simple and general technique, based on reduction to a concensus protocol, for proving statements of the form, “there is no wait-free implementation of X by Y.” We derive a hierarchy of objects such that no object at one level has a wait-free implementation in terms of objects at lower levels. In particular, we show that atomic read/write registers, which have been the focus of much recent attention, are at the bottom of the hierarchy: thay cannot be used to construct wait-free implementations of many simple and familiar data types. Moreover, classical synchronization primitives such astest&set and fetch&add, while more powerful than read and write, are also computationally weak, as are the standard message-passing primitives. Second, nevertheless, we show that there do exist simple universal objects from which one can construct a wait-free implementation of any sequential object.

Abstract: With contributions from Tomas LozanoPerez and Daniel P. Huttenlocher.An intelligent system must know "what "the objects are and "where "they are in its environment. Examples of this ubiquitous problem in computer vision arise in tasks involving hand-eye coordination (such as assembling or sorting), inspection tasks, gauging operations, and in navigation and localization of mobile robots. This book describes an extended series of experiments into the role of geometry in the critical area of object recognition. It provides precise definitions of the recognition and localization problems, describes the methods used to address them, analyzes the solutions to these problems, and addresses the implications of this analysis.The solution to problems of object recognition are of fundamental importance in many real applications and versions of the techniques described here are already being used in industrial settings. Although a number of questions remain to be solved, the authors provide a valuable framework for understanding both the strengths and limitations of using object shape to guide recognition.W. Eric L. Grimson is Matsushita Associate Professor in the Department of Electrical Engineering and Computer Science at MIT.Contents: Introduction. Recognition as a Search Problem. Searching for Correspondences. Two-Dimensional Constraints. Three-Dimensional Constraints. Verifying Hypotheses. Controlling the Search Explosion. Selecting Subspaces of the Search Space. Empirical Testing. The Combinatorics of the Matching Process. The Combinatorics of Hough Transforms. The Combinatorics of Verification. The Combinatorics of Indexing. Evaluating the Methods. Recognition from Libraries. Parameterized Objects. The Role of Grouping. Sensing Strategies. Applications. The Next Steps.

Abstract: A multi-user collaborative system in which the contents as well as the current status of other user activity of a shared structured data object representing one or more related structured data objects in the form of data entries can be concurrently accessed by different users respectively at different workstations connected to a common link. The WYSIWIS user interface representation of the shared structured data object includes an ordered listing of such entries that are maintained by the structured data object and various attributes of each listed entry, inter alia, the type and class of entry; the revision number of the shared structured data object; the number of pages and revision number of each structured data object entry; the date of creation and last revision of each such entry; whether an entry can be accessed by a user and, if not, who has prevented such access; whether a local instance of an entry is present on a user's system; and a provision for miscellaneous notes or comments relative to each entry for view by other users. Means is provided for maintaining current information relative to the shared structured object and its entries on a user initiated demand updated basis invoked by a user operation, which operation requires updated information to properly implement the operation. Further, means is provided for locking up one or more data entries by an individual user and thereby prevent access of the locked entries by other users to prevent concurrent editing and other changes to the same entries by two or more users. In this connection, editing or modification cannot be performed by a user until the shared structured data object entry or entries have been locked up. Visual indication as to the locked state of entries and other information relative to the locking user and the time of lock is updated and displayed in the shared structured data object representation present at user workstations when a use invokes a user operation on the shared structured data object or its contents.

Abstract: A computer user interface that represents information stored in a computer as reprentation objects located on at least one reference surface is disclosed. A user can magnify or reduce the displayed information by "zooming" in or out. The magnification operation displays a smaller portion of a particular surface, but each object that remains in view is displayed in greater size and/or detail. Similarly, the reduction operation displays a larger portion of a given surface, but each object within such surface is displayed in a smaller size and/or less detail. In order to view one part of the surface from another part of the surface or from another surface, a special type of an object, called a representation portal object, is provided. A graphical description of each object is physically stored in computer memory essentially as a sequence of compressed image representations. The first image in the sequence is a bit-mapped representation of an object as it was created, and each subsequent image is a reduced copy of the first image.

Abstract: A system and method for database management for providing support for long-term storage and retrieval of objects created by application programs written at least in part in object-oriented programming languages consists of a plurality of software modules. These modules provide data definition language translation, object management, object translation, and persistent object storage service. Such system implements an object fault capability to reduce the number of interactions between the application, the database management system, and the database.

Abstract: A method is disclosed for providing user access control for a plurality of resource objects within a distributed data processing system having a plurality of resource managers. A reference monitor service is established and a plurality of access control profiles are stored therein. Thereafter, selected access control profiles are exchanged between the reference monitor service and a resource manager in response to an attempted access (82) of a particular resource object controlled by that resource manager. The resource manager may then control access to the resource object by utilizing the exchanged access control profile (86-98). In a preferred embodiment of the present invention, each access control profile may include access control information relating to a selected user; a selected resource object; a selected group of user; a selected set of resource objects; or, a predetermined set of resource objects and a selected group of users.

Abstract: The system and method of this invention provides an access control list which spans across object boundaries in an object oriented database. In addition to providing read and write access permissions, the access control list provides execute semantics which apply to the execution of methods in an object oriented database. Within the entries of the access control lists, each of the permissions for read, write, and execute can be assigned separately to each of a number of ids representing user ids or group ids. Upon request for access to the data by the user, the user id of the user and the group ids for which the user is a member are searched for within the entries to determine whether the user has the privileges to perform the operation requested against the objects. In addition, the access control policies are inherited from an object's superobject; resulting in a least privilege for the object.

Abstract: A sensing system for monitoring the position and orientation of a rigid object (20). At least 4 point light sources (24) are mounted on the surface of the object (20) in a noncoplanar arrangement. A single electronic camera (26) captures images (59) of the point light sources (24). Locations of the images (59) of the light sources (24) are detected in each video image, and a computer runs a task using these locations to obtain close approximations of the rotation matrix and translation vector (33) of the object (20) in a camera coordinate system (74) at video rate. The object is held by an operator (90) for three-dimensional cursor (94) control and interaction with virtual reality scenes (96) on computer displays (88), and for remote interactive control of teleoperated mechanisms.

Abstract: In distributed heterogeneous data processing networks, dispatcher and control server software components execute the code of a single application or of many portions of the code of one or more applications in response to a method object received from a client application. The method object includes a reference to the code to be executed.

Abstract: The development of distributed operating systems and object-based programming languages makes possible an environment in which programs consisting of a set of interacting modules, or objects, may execute concurrently on a collection of loosely coupled processors. An object-based programming language encourages a methodology for designing and creating a program as a set of autonomous components, whereas a distributed operating system permits a collection of workstations or personal computers to be treated as a single entity. The amalgamation of these two concepts has resulted in systems that shall be referred to as distributed, object-based programming systems.This paper discusses issues in the design and implementation of such systems. Following the presentation of fundamental concepts and various object models, issues in object management, object interaction management, and physical resource management are discussed. Extensive examples are drawn from existing systems.

Abstract: A declarative object-oriented approach to menu construction provides a mechanism for specifying the behavior, appearance and function of menus as part of an interactive user interface. Menus are constructed from interchangeable object building blocks to obtain the characteristics wanted without the need to write new code or code and maintaining a coherent interface standard. The approach is implemented by dissecting interface menu behavior into modularized objects specifying orthogonal components of desirable menu behaviors. Once primary characteristics for orthogonal dimensions of menu behavior are identified, individual objects are constructed to provide specific alternatives for the behavior within the definitions of each dimension. Finally, specific objects from each dimension are combined to construct a menu having the desired selections of menu behaviors.

Abstract: A board game apparatus comprises a board 10 marked with a seven-by-seven array 12 of squares having an inner five-by-five region 14 and a peripheral region 16. Two players play each using, for example, eighteen playing pieces and two blocking pieces, with the object to cause four of the opposing playing pieces to be arranged in a square of four adjacent locations in the inner region. There are four key locations 20 and two pegging regions 22.

Abstract: A method and system for controlling access by groups of users to multiple objects stored within a data processing system implemented library wherein each object has an access list associated therewith explicitly listing individual users permitted access to that object. A group identification is established which encompasses all users within the data processing system, a selected subset of users with the data processing system, or a single selected user and his or her designated affinity users or proxies. The group identification is then listed within an associated access list for a particular object and upon an attempted access of the particular object by a user not listed explicitly within the associated access list, a determination is made as to whether or not that user is listed within a group identification which is permitted access. In one embodiment of the present invention selected objects and users each have associated therewith a clearance level and access to a selected object by a particular user listed within a group identification may be denied if that particular user's clearance level does not meet or exceed the clearance level of the selected object.

Abstract: An object based data processing system including an extensible set of object types and a corresponding set of "object managers" wherein each object manager is a program for operating with the data stored in a corresponding type of object. The object managers in general support at least a standard set of operations. Any program can effect performance of these standard operations on objects of any type by making an "invocation" request. In response to an invocation request, object management services (which are available to all object managers) identifies and invokes an object manager that is suitable for performing the requested operation on the specified type of data. A mechanism is provided for linking data from one object into another object. An object catalog includes both information about objects and about links between objects. Data interchange services are provided for communicating data between objects of different types, using a set of standard data interchange formats. A matchmaker facility permits two processes that are to cooperate in a data interchange operation identify each other and to identify data formats they have in common. A facility is provided for managing shared data "resources". Customized versions of resources can be created and co-exist with standard resources. A resource retrieval function determines whether a customized or a standard resource is to be returned in response to each request for a resource.

Abstract: The topic of model-building for 3-D objects is examined. Most 3-D object recognition systems construct models either manually or by training. Neither approach has been very satisfactory, particularly in designing object recognition systems which can handle a large number of objects. Recent interest in integrating mechanical CAD systems and vision systems has led to a third type of model building for vision: adaptation of preexisting CAD models of objects for recognition. If a solid model of an object to be recognized is already available in a manufacturing database, then it should be possible to infer automatically a model appropriate for vision tasks from the manufacturing model. Such a system has been developed. It uses 3-D object descriptions created on a commercial CAD system and expressed in both the industry-standard IGES form and a polyhedral approximation and performs geometric inferencing to obtain a relational graph representation of the object which can be stored in a database of models for object recognition. Relational graph models contain both view-independent information extracted from the IGES description and view-dependent information (patch areas) extracted from synthetic views of the object. It is argued that such a system is needed to efficiently create a large database (more than 100 objects) of 3-D models to evaluate matching strategies. >

Abstract: Model-based recognition methods generally use ad hoc techniques to decide whether or not a model of an object matches a given scene. The most common such technique is to set an empirically determined threshold on the fraction of model features that must be matched to data features. Conditions under which to accept a match as correct are rigorously derived. The analysis is based on modeling the recognition process as a statistical occupancy problem. This model makes the assumption that pairings of object and data features can be characterized as a random process with a uniform distribution. The authors present a number of examples illustrating that real image data are well approximated by such a random process. Using a statistical occupancy model, they derive an expression for the probability that a randomly occurring match will account for a given fraction of the features of a particular object. This expression is a function of the number of model features, the number of data features, and bounds on the degree of sensor noise. It provides a means of setting a threshold such that the probability of a random match is very small. >

Abstract: A system and method of logically and physically clustering data (tuples) in a database. The database management system of the invention partitions (declusters) a set of relations into smaller so-called local relations and reclusters the local relations into constructs called domains. The domains are self-contained in that a domain contains the information for properly accessing and otherwise manipulating the data it contains. In other words, the data objects stored in the domains may be stored in a particular domain based upon a locality-of-reference algorithm in which a tuple of data is placed in a domain if and only if all objects referenced by the tuple are contained in the domain. On the other hand, the data objects stored in a domain may be clustered so that a tuple of data is placed in a domain based on the domain of the object referenced by a particular element of the tuple. By clustering the related object data in this manner, the database management system may more efficiently cache data to a user application program requesting data related to a particular data object. The system may also more efficiently lock and check-in and check-out data from the database so as to improve concurrency. Moreover, versioning may be more readily supported by copying tuples of a particular domain into a new domain which can then be updated as desired.

Abstract: A scanning system for a three-dimensional object digitizing system comprises circuitry for directing a set of sequential light beams to a plurality of points on an object The light beams are directed by the normalizing circuitry to be normal to the surface of the object at the point of incidence With this orientation, the scanning system associates with the ranging system for the determination of a set of a range measurements to the points on the object Circuitry of the scanning system predicts the location of a point on the surface as a function of a plurality of previously measured points Additional circuitry adaptively pivots the light beams away from the normal incidence angle to reach a plurality of points in response to a measurement substantially deviating from the predicted point The scanning system redirects subsequent light beams to be incident on the surface upon the occurrence of a predetermined set of conditions and continues to provide normal incidence angles and pivoting incidence angles for points around the contour of the object being scanned

Abstract: In a data communication network, a method and apparatus for determining routing in a diagnostic channel utilizes a search token which is passed through nodes of a memory model of the network. The memory model represents nodes as one (or a combination of) object models representing aggregation, deaggregation, mesh or translation operations. By referring to a relational database, selective searches are performed without need to flood the network with search tokens. The search results may be displayed graphically for easier understanding. The method also has general application to a relational database management system by allowing for display of the database relationships and interconnections in a graphical manner for easier interpretation by the user.

Abstract: A system for routing an "object" (in the sense that object means an abstraction that encapsulates data in a known way, with a known list of operations or methods to access the data, and the object has a unique identity, is mobile, and possibly persistent). The "object" is routed in a distributed computing system along an action path (itself an "object") which defines the logical path to be traversed by the object. The action path consists of action stops naming or describing functionally principals (people or automated mechanisms) required to act upon the routed object in a prescribed order. The object routing system propagates the object along this action path, and monitors and controls its progress until it completes the path. The system includes mechanisms of dispatching the routed object between principals, finding the principals required to act on the routed object, notifying the principals in turn of their required action, and potentially relocating the routed object to the nodes of the principals. Optionally, the object routing system may use mechanisms for nagging principals about pending actions (if no progress occurs within a specified period), reporting such lack of action or progress to other principals, supporting the sharing of an action path by multiple routed objects, and facilitating the routing of an object in parallel to multiple principals. This object routing system is constructed as a generic service layer above services for object management, migration, persistence and interobject communication.

Abstract: A method and object-oriented architecture for interfacing a user to a relational database system The contour of the interface is defined by a profile object and a task object. The profile object, in response to user selection, defines one of multiple role objects with associated user proficiency and system behavioral characteristics. The task object responds to parameters derived from the profile object to generating a query for the relational database system. In one form, the task object includes one or more functional objects suitable to query the database. Representative functional objects are the domain object (used to formulate problem oriented queries), the analysis object (used to analyze the data extracted from the database), the report object (used to generate a user response format), and the link object (used to relate the components within the task object). The interface according to the invention matches the abilities of the user to the resources of the database system, manipulates problem oriented high-level queries, and provides an object oriented architecture readily amenable to object refinement.

Abstract: Method and apparatus are disclosed for determining the position and attitude of objects, together with robotic systems employing same, and methods of targeting objects for such purposes. Particularly of interest is the application to continuous conveyors, particularly in the process of automobile manufacture. Also disclosed is the use of naturally occuring object features as targets in a machine vision based robot (or other) guidance system. In one embodiment, a special high speed processor finds at least 3 preselected feature points on an object, which when considered with the data base for the object, allows a rapid 6 degree of freedom solution for the object location relative to the camera and thence connected automation. While primarily envisioned for industrial robots, the invention is useful for all sorts of machines including vehicles, construction machinery and the like--anywhere the target object has a known data base relative to the features in question.

Abstract: Object-oriented data models are receiving wide attention since they provide expressive abstraction mechanisms to model naturally and directly both structural and behavioral aspects of complex databases applications. In an objectoriented data model, a database is modeled in terms of objects grouped in classes, organized into subclasses hierarchies. Moreover, associations between entities are modeled by defining properties of objects whose value is the related object. However this way of modeling associations has several limitations which make the description of some aspects of associations unnatural. To overcome these limitations an object-relationship data model is proposed which supports both the mechanisms of an objectoriented data model and a separate mechanism to model explicitly associations and to express declaratively common constraints on them. Constructs to support this model for a statically and strongly typed object-oriented database programming language are defined.

Abstract: Generally, in one form of the invention, a computer system for executing application programs in hard real-time, comprises a central processing unit (CPU) for executing the application programs and system programs and a computer memory partitioned into a data memory and a code memory. A garbage collector, which executes on said CPU, places a write barrier over certain portions of memory. Furthermore, it transfers an object from a location in the memory to a second object at another location in the memory. In a critical section, which may not be interrupted, it allocates sufficient space for the second object so that the entire contents from the first object can be copied into the second object, and in an interruptable section, it copies the entire contents of the first object into the second object. A write routine is linked into the application programs for updating objects in the computer memory. The write routine is operable to update both the first object and the second object whenever the garbage collector is transferring the contents of the object into the second object. Both copies are thereby kept current.

Abstract: An improved document processing system is disclosed wherein objects such as text areas, numerical tables or graphic data may be assigned a fixed location within a document. The system automatically allocates layout areas that surround the fixed areas without overlapping. Means are provided for linking text from one side of a fixed object to the other side while automatically maximizing the area available for free text or other objects. The invention allows an infinite number of fixed objects, and automatically generates page layout. In addition, the invention allows the user to set page size, page margins, and the size of fixed-position objects relative to page size. The system allows the use of numerous page formats, including multiple columns, and then automatically generates page layouts where the text area is maximized. These steps require a minimum of interaction with the user.

Abstract: Identification of a target object within an object hierarchy is made in response to user selection. The prior attribute values for the target object are then displayed on a display device. Upon user selection, new object attribute values are generated for the target object. A propagation group for the new object attribute values is made in response to user designation of relating factors and the new object attribute values are applied to all objects within the related group.

Abstract: A static Entity-Relationship (ER) or static Extended ER (EER) data model is not sufficient for representing the underlying time component of the data, more complex data types as found in planning, design and office automation applications or the operation required for this complex data. The decreasing cost of mass storage devices accompanied by an increased need for real-time systems and easier access to historical and planning data has made the study of the temporal aspects of data models more interesting both theoretically and practically. Furthermore, the ER-based data models can capture relationships between classes but they do not understand the object-oriented paradigm since they treat application-specific relationships and paradigm-specific relationships such as inheritance in the same manner. This shortcoming accompanied by a lack of support for the time dimension results in the specification of temporal relationships and constraints at the application level and often leads to inconsistencies in the data. In this paper, we extend the object-based ER model into a temporal, object-oriented model, incorporate temporal structures and constraints in the data model and propose a temporal, object-oriented query language for the model.