Functions and Frames in the Learning of Structures

Work reported herein was conducted at the Artificial Intelligence Laboratory, a Massachusetts Institute of Technology research program supported in part by the Advanced Research Projects Agency of the Department of Defense and monitored by the Office of Naval Research under Contract Number N00014-70-A-0362-0005.This paper discusses methods for enhancing the learning abilities of the Winston program, first by representing functional properties of the objects considered, and secondly by embedding individual models in a hierarchically organized system to provide for economy of recognition. An example is presented illustrating the use of these methods.MIT Artificial Intelligence Laborator

VNS -- a virtual network simulator

A software system to study network algorithms was implemented on UNIX. Each part of a network algorithm can be written as a single C program which becomes a virtual node in the network. During a simulation all virtualized nodes run as separate processes on a single PDP 11/44. Inter-node communication is carried out with procedures local to each node, to send and receive inter-node messages to and from a message queuing process. Communication between nodes is effected by use of virtual links which are specified in the simulated network's topology. The links are implemented on inter-process pipes between the mess-age queuing process and the node processes. Run-time support routines include communication facilities and a mechanism for recording communication histories

Particularity in engineering data

A database to be used by electrical circuit design, test, and repair expert systems must support both structural data and inferential data about the circuit. It is well known that engineering databases must support dynamic schema (re)definition of the structural data and entity-based access to it. We analyze this requirement and show that the underlying principle is one of particularity, applied to the operations of definition and access. We· then examine three types of inferential data for engineering expert system databases and show that the use of this inferential data exhibits a close parallel that of the structural data. Thus, the concepts of particularity of definition and particularity of access carry over to the inferential data. We conclude that these are the underlying phenomena which motivate the choice of an an object-oriented data model as the appropriate framework for engineering expert system databases

KurSL: model of anharmonic coupled oscillations based on Kuramoto coupling and Sturm–Liouville problem

Physiological signaling is often oscillatory and shows nonlinearity due to complex interactions of underlying processes or signal propagation delays. This is particularly evident in case of brain activity which is subject to various feedback loop interactions between different brain structures, that coordinate their activity to support normal function. In order to understand such signaling in health and disease, methods are needed that can deal with such complex oscillatory phenomena. In this paper, a data-driven method for analyzing anharmonic oscillations is introduced. The KurSL model incorporates two well-studied components, which in the past have been used separately to analyze oscillatory behavior. The Sturm–Liouville equations describe a form of a general oscillation, and the Kuramoto coupling model represents a set of oscillators interacting in the phase domain. Integration of these components provides a flexible framework for capturing complex interactions of oscillatory processes of more general form than the most commonly used harmonic oscillators. The paper introduces a mathematical framework of the KurSL model and analyzes its behavior for a variety of parameter ranges. The significance of the model follows from its ability to provide information about coupled oscillators’ phase dynamics directly from the time series. KurSL offers a novel framework for analyzing a wide range of complex oscillatory behaviors, such as the ones encountered in physiological signals

Skew-self-adjoint discrete and continuous Dirac type systems: inverse problems and Borg-Marchenko theorems

New formulas on the inverse problem for the continuous skew-self-adjoint Dirac type system are obtained. For the discrete skew-self-adjoint Dirac type system the solution of a general type inverse spectral problem is also derived in terms of the Weyl functions. The description of the Weyl functions on the interval is given. Borg-Marchenko type uniqueness theorems are derived for both discrete and continuous non-self-adjoint systems too

Generalized Ricci Curvature Bounds for Three Dimensional Contact Subriemannian manifolds

Measure contraction property is one of the possible generalizations of Ricci curvature bound to more general metric measure spaces. In this paper, we discover sufficient conditions for a three dimensional contact subriemannian manifold to satisfy this property.Comment: 49 page

Inverse spectral problems for Sturm-Liouville operators with singular potentials

The inverse spectral problem is solved for the class of Sturm-Liouville operators with singular real-valued potentials from the space $W^{-1}_2(0,1)$. The potential is recovered via the eigenvalues and the corresponding norming constants. The reconstruction algorithm is presented and its stability proved. Also, the set of all possible spectral data is explicitly described and the isospectral sets are characterized.Comment: Submitted to Inverse Problem