Fifth generation computers

Fifth generation computers are analogous to LEGO building blocks, with each block corresponding to a microcomputer and a group of blocks working together as a computer system. These computers will represent a unification of currently separate areas of research into parallel processing and into VLSI processors. Parallel processing based on data driven and demand driven computer organisations are under investigation in well over thirty laboratories in the United States, Japan and Europe. Basically, in data driven (e.g. data flow) computers the availability of operands triggers the execution of the operation to be performed on them; whereas in demand driven (e.g. reduction) computers the requirement for a result triggers the operation that will generate the value. VLSI processors exploit very large scale integration and the new simplified chip design methodology pioneered in US universities by Mead and Conway, allowing users to design their own chips. These novel VLSI processors are implementable by simple replicated cells and use extensive pipelining and multiprocessing to achieve a high performance. Examples range from a powerful image processing device configured from identical special-purpose chips, to a large parallel computer built from replicated general-purpose microcomputers. This paper outlines these topics contributing to fifth generation computers, and speculates on their effect on computing.     

Property-directed incremental invariant generation

A fundamental method of analyzing a system such as a program or a circuit is invariance analysis, in which one proves that an assertion holds on all reachable states. Typically, the proof is performed via induction; however, an assertion, while invariant, may not be inductive (provable via induction). Invariant generation procedures construct auxiliary inductive assertions for strengthening the assertion to be inductive. We describe a general method of generating invariants that is incremental and property-directed. Rather than generating one large auxiliary inductive assertion, our method generates many simple assertions, each of which is inductive relative to those generated before it. Incremental generation is amenable to parallelization. Our method is also property-directed in that it generates inductive assertions that are relevant for strengthening the given assertion. We describe two instances of our method: a procedure for generating clausal invariants of finite-state systems and a procedure for generating affine inequalities of numerical infinite-state systems. We provide evidence that our method scales to checking safety properties of some large finite-state systems.     

Field functions for implicit surfaces

The use of 3D computer generated models is a rapidly growing part of the animation industry. But the established modelling techniques, using polygons or parametric patches, are not the best to define characters which can change their shape as they move. A newer method, using iso-surfaces in a scalar field, enables us to create models that can make the dynamic shape changes seen in hand animation. We call such modelsSoft Objects.From the user's point of view, a soft object is built from primitive key objects that blend to form a compound shape. In this paper, we examine some of the problems of choosing suitable keys and introduce some new field functions that increase the range of shapes available as keys.     

Runtime incremental parallel scheduling (RIPS) on distributedmemory computers

Runtime Incremental Parallel Scheduling (RIPS) is an alternative strategy to the commonly used dynamic scheduling. In this scheduling strategy, the system scheduling activity alternates with the underlying computation work. RIPS utilizes the advanced parallel scheduling technique to produce a low overhead, high quality load balancing, as well as adapting to irregular applications. The paper presents methods for scheduling a single job on a dedicated parallel machine     

The architecture of fifth generation inference computers

The architecture of the FGCs sequential and parallel inference machines are described.     

Towards incremental speech generation in conversational systems

This paper presents a model of incremental speech generation in practical conversational systems. The model allows a conversational system to incrementally interpret spoken input, while simultaneously planning, realising and self-monitoring the system response. If these processes are time consuming and result in a response delay, the system can automatically produce hesitations to retain the floor. While speaking, the system utilises hidden and overt self-corrections to accommodate revisions in the system. The model has been implemented in a general dialogue system framework. Using this framework, we have implemented a conversational game application. A Wizard-of-Oz experiment is presented, where the automatic speech recognizer is replaced by a Wizard who transcribes the spoken input. In this setting, the incremental model allows the system to start speaking while the user's utterance is being transcribed. In comparison to a non-incremental version of the same system, the incremental version has a shorter response time and is perceived as more efficient by the users.     

Program generation system for modern hybrid computers

This paper describes the use of a new integrated hybrid programming system which provides equation oriented specification of continuous system simulation models and automated setup, checkout, and operation of the hybrid computer. The programming system is based upon the APBE compiler originally developed through the National Computing Center in England and the HYTRAN Operations Interpreter (HOI) implemented on EAI hybrid computers. In the new program generation system, both processors have been enhanced to enrich the languages and to provide compatible file processing so that the compiler generates a complete HYTRAM object program file which is processed on-line by the hybrid system for setup, checkout, and operation of the analog processor. The benefits of this automatic program generation over the manual process include significant reduction of programming time and cost, error free program setup and operation, and increased hybrid computer productivity.     

Parallel three-dimensional mesh generation on distributed memory MIMD computers

This paper discusses the development of an automatic mesh generation technique designed to operate effectively on multiple instruction multiple data (MIMD) parallel computers. The meshing approach is hierarchical, that is, model entities are meshed after their boundaries have been meshed. Focus is on the region meshing step. An octree is constructed to serve as a localization tool and for efficiency. The tree is also key to the efficient parallelization of the meshing process since it supports the distribution of load to processors. The parallel mesh generation procedure repartitions the domain to be meshed and applies on processor face removals until all face removals with local data have been performed. The portion of the domain to be meshed remaining is dynamically repartitioned at the octant level using an Inertial Recursive Bisection method and local face removals are reperformed. Migration of a terminal octant involves migration of the octant data and the octant's mesh faces and/or mesh regions. Results show relatively good speed-ups for parallel face removals on small numbers of processors. Once the three-dimensional mesh has been generated, mesh regions may be scattered across processors. Therefore, a final dynamic repartitioning step is applied at the region level to produce a partition ready for finite element analysis.     

Interpretation and generation incremental management in natural interaction systems

Human interaction develops as an exchange of contributions between participants. The construction of a contribution is not an activity unilaterally created by the participant who produces it, but rather it constitutes a combined activity between the producer and the rest of the participants who take part in the interaction, by means of simultaneous feedback. This paper presents an incremental approach (without losing sight of how turns are produced throughout time), in which the interpretation of contributions is done as they take place, and the final generated contributions are the result of constant rectifications, reformulations and cancellations of the initially formulated contributions. The Continuity Manager and the Processes Coordinator components are proposed. The integration of these components in natural interaction systems allow for a joint approach to these problems. Both have been implemented and evaluated in a real framework called LaBDA-Interactor System which has been applied to the “dictation domain”. We found that the degree of naturalness of this turn-taking approach is very close to the human one and it significantly improves the interaction cycle.     

On simultaneous generation of sensitivity functions

The purpose of this correspondence is to prove by using the Laplace transform the fact that the first-order sensitivity functions of the phase variable canonical system have two useful properties, "symmetry and simultaneity," indicated by Wilkie and Perkins. It is also demonstrated that the second-order sensitivity functions of the system have the same properties.     

Interactive 3D medical image segmentation with energy-minimizing implicit functions

We present an interactive segmentation method for 3D medical images that reconstructs the surface of an object using energy-minimizing, smooth, implicit functions. This reconstruction problem is called variational interpolation. For an intuitive segmentation of medical images, variational interpolation can be based on a set of user-drawn, planar contours that can be arbitrarily oriented in 3D space. This also allows an easy integration of the algorithm into the common manual segmentation workflow, where objects are segmented by drawing contours around them on each slice of a 3D image.Because variational interpolation is computationally expensive, we show how to speed up the algorithm to achieve almost real-time calculation times while preserving the overall segmentation quality. Moreover, we show how to improve the robustness of the algorithm by transforming it from an interpolation to an approximation problem and we discuss a local interpolation scheme.A first evaluation of our algorithm by two experienced radiology technicians on 15 liver metastases and 1 liver has shown that the segmentation times can be reduced by a factor of about 2 compared to a slice-wise manual segmentation and only about one fourth of the contours are necessary compared to the number of contours necessary for a manual segmentation.     

Mesh size functions for implicit geometries and PDE-based gradient limiting

Mesh generation and mesh enhancement algorithms often require a mesh size function to specify the desired size of the elements. We present algorithms for automatic generation of a size function, discretized on a background grid, by using distance functions and numerical PDE solvers. The size function is adapted to the geometry, taking into account the local feature size and the boundary curvature. It also obeys a grading constraint that limits the size ratio of neighboring elements. We formulate the feature size in terms of the medial axis transform, and show how to compute it accurately from a distance function. We propose a new Gradient Limiting Equation for the mesh grading requirement, and we show how to solve it numerically with Hamilton–Jacobi solvers. We show examples of the techniques using Cartesian and unstructured background grids in 2D and 3D, and applications with numerical adaptation and mesh generation for images.

Stereo by incremental matching of contours

Contours made of sequences of adjacent edge points are used as primitives in stereo pair matching. Matching contour segments, rather than the traditional epipolar edge points, can greatly reduce possible ambiguity. This is done by reformulating point-matching constraints to apply to contour matching, and by introducing a unique incremental matching scheme. Best-matched contours are paired first, constraining through neighborhood support their neighboring contours. Examples of the proposed stereo matching scheme are shown, with very few errors, for aerial images of natural terrain