Howard Shrobe

AAAI Conference 2015 Conference Paper

Towards a Programmer’s Apprentice (Again)

• Howard Shrobe
• Boris Katz
• Randall Davis

AAAI Conference 2002 Conference Paper

Computational Vulnerability Analysis for Information Survivability

• Howard Shrobe

The Infrastructure of modern society is controlled by software systems. These systems are vulnerable to attacks; several such attacks, launched by "recreation hackers" have already led to severe disruption. However, a concerted and planned attack whose goal is to reap harm could lead to catastrophic results (for example, by disabling the computers that control the electrical power grid for a sustained period of time). The survivability of such information systems in the face of attacks is therefore an area of extreme importance to society. This paper is set in the context of self-adaptive survivable systems: software that judges the trustworthiness of the computational resources in its environment and which chooses how to achieve its goals in light of this trust model. Each self-adaptive survivable system detects and diagnoses compromises of its resources, taking whatever actions are necessary to recover from attack. In addition, a long-term monitoring system collects evidence from intrusion detectors, fire-walls and all the self-adaptive components, building a composite trust-model used by each component. Self-adaptive surviable systems contain models of their intended behavior, models of the required computational resources, models of the ways in which these resources may be compromised and finally, models of the ways in which a system may be attacked and how such attacks can lead to compromises of the computational resources. In this paper we focus on Computational Vulnerability Analysis: a system that, given a description of a computational environment, deduces all of the attacks that are possible. In particular its goal is to develop multi-stage attack models in which the compromise of one resource is used to facilitate the compromise of other, more valuable resources. Although our ultimate aim is to use these models online as part of a self-adaptive system, there are other offline uses as well which we are deploying first to help system administrators assess the vulnerabilitities of their computing environment.

AIJ Journal 2000 Journal Article

Qualitative rigid-body mechanics

• Thomas F. Stahovich
• Randall Davis
• Howard Shrobe

We present a theory of qualitative rigid-body mechanics and describe a program that uses this theory to compute qualitative rigid-body dynamic simulations. The program works directly from a qualitative representation of geometry—qualitative configuration space—without need of any metric information. The program can handle devices that are composed of an arbitrary number of fixed-axis components and springs, with driving inputs coming from both applied motions and forces. The program employs quasi-static assumptions, i. e. , inertia-free motion, inelastic collisions, and frictionless contacts. It employs a new qualitative representation for forces that reduces ambiguity in force sums and hence reduces unnecessary branching.

AIJ Journal 1998 Journal Article

Generating multiple new designs from a sketch

• Thomas F. Stahovich
• Randall Davis
• Howard Shrobe

We describe a program called SketchIT that transforms a single sketch of a mechanical device into multiple families of new designs. It represents each of these families with a “BEP-Model”, a parametric model augmented with constraints that ensure the device produces the desired behavior. The program is based on qualitative configuration space (qc-space), a novel representation that captures mechanical behavior while abstracting away its implementation. The program employs a paradigm of abstraction and resynthesis: it abstracts the initial sketch into qc-space, then uses a library of primitive mechanical interactions to map from qc-space to new implementations.