Problem Solving
SAT Solvers and Computer Algebra Systems: A Powerful Combination for Mathematics
Bright, Curtis, Kotsireas, Ilias, Ganesh, Vijay
Over the last few decades, many distinct lines of research aimed at automating mathematics have been developed, including computer algebra systems (CASs) for mathematical modelling, automated theorem provers for first-order logic, SAT/SMT solvers aimed at program verification, and higher-order proof assistants for checking mathematical proofs. More recently, some of these lines of research have started to converge in complementary ways. One success story is the combination of SAT solvers and CASs (SAT+CAS) aimed at resolving mathematical conjectures. Many conjectures in pure and applied mathematics are not amenable to traditional proof methods. Instead, they are best addressed via computational methods that involve very large combinatorial search spaces. SAT solvers are powerful methods to search through such large combinatorial spaces---consequently, many problems from a variety of mathematical domains have been reduced to SAT in an attempt to resolve them. However, solvers traditionally lack deep repositories of mathematical domain knowledge that can be crucial to pruning such large search spaces. By contrast, CASs are deep repositories of mathematical knowledge but lack efficient general search capabilities. By combining the search power of SAT with the deep mathematical knowledge in CASs we can solve many problems in mathematics that no other known methods seem capable of solving. We demonstrate the success of the SAT+CAS paradigm by highlighting many conjectures that have been disproven, verified, or partially verified using our tool MathCheck. These successes indicate that the paradigm is positioned to become a standard method for solving problems requiring both a significant amount of search and deep mathematical reasoning. For example, the SAT+CAS paradigm has recently been used by Heule, Kauers, and Seidl to find many new algorithms for $3\times3$ matrix multiplication.
Solving Service Robot Tasks: UT Austin Villa@Home 2019 Team Report
Shah, Rishi, Jiang, Yuqian, Karnan, Haresh, Briscoe-Martinez, Gilberto, Mulder, Dominick, Gupta, Ryan, Schlossman, Rachel, Murphy, Marika, Hart, Justin W., Sentis, Luis, Stone, Peter
RoboCup@Home is an international robotics competition based on domestic tasks requiring autonomous capabilities pertaining to a large variety of AI technologies. Research challenges are motivated by these tasks both at the level of individual technologies and the integration of subsystems into a fully functional, robustly autonomous system. We describe the progress made by the UT Austin Villa 2019 RoboCup@Home team which represents a significant step forward in AI-based HRI due to the breadth of tasks accomplished within a unified system. Presented are the competition tasks, component technologies they rely on, our initial approaches both to the components and their integration, and directions for future research.
The Role of AI in Industry: UoB Business Club Breakfast Briefing
Join UoB Business Club for valuable insight into applications of Artificial Intelligence (AI) in industry and discover the support available from the University of Birmingham and the Science & Technologies Facilities Council to businesses seeking to investigate potential applications of AI in their processes. Complimentary breakfast is included in this free event. Mohan is a Senior Lecturer in the School of Computer Science. His primary research interests include knowledge representation and reasoning, machine learning, computer vision and cognitive systems as applied to autonomous robots and adaptive agents. Mohan develops architectures and algorithms that enable robots to collaborate with non-expert human participants, acquiring and using sensor inputs and high-level human feedback based on need and availability.
Developing Computational Models of Social Assistance to Guide Socially Assistive Robots
Wilson, Jason R., Kim, Seongsik, Kurylo, Ulyana, Cummings, Joseph, Tarneja, Eshan
While there are many examples in which robots provide social assistance, a lack of theory on how the robots should decide how to assist impedes progress in realizing these technologies. To address this deficiency, we propose a pair of computational models to guide a robot as it provides social assistance. The model of social autonomy helps a robot select an appropriate assistance that will help with the task at hand while also maintaining the autonomy of the person being assisted. The model of social alliance describes how a to determine whether the robot and the person being assisted are cooperatively working towards the same goal. Each of these models are rooted in social reasoning between people, and we describe here our ongoing work to adapt this social reasoning to human-robot interactions. Socially assistive robots (SARs) provide social assistance instead of physically intervening.
Abstraction for Zooming-In to Unsolvability Reasons of Grid-Cell Problems
Eiter, Thomas, Saribatur, Zeynep G., Schรผller, Peter
Humans are capable of abstracting away irrelevant details when studying problems. This is especially noticeable for problems over grid-cells, as humans are able to disregard certain parts of the grid and focus on the key elements important for the problem. Recently, the notion of abstraction has been introduced for Answer Set Programming (ASP), a knowledge representation and reasoning paradigm widely used in problem solving, with the potential to understand the key elements of a program that play a role in finding a solution. The present paper takes this further and empowers abstraction to deal with structural aspects, and in particular with hierarchical abstraction over the domain. We focus on obtaining the reasons for unsolvability of problems on grids, and show the possibility to automatically achieve human-like abstractions that distinguish only the relevant part of the grid. A user study on abstract explanations confirms the similarity of the focus points in machine vs. human explanations and reaffirms the challenge of employing abstraction to obtain machine explanations.
Allen Institute for AI Announces BERT-Breakthrough: Passing an 8th-Grade Science Exam - NVIDIA Developer News Center
This week the Allen Institute for Artificial Intelligence announced a breakthrough for a BERT-based model, passing an eighth-grade science test. The GPU-accelerated system called Aristo can read, learn, and reason about science, in this case emulating the decision making of students. For this milestone, Aristo answered more than 90 percent of the questions on an eighth-grade science exam correctly, and 83 percent on a 12th-grade exam. "Although Aristo only answers multiple choice questions without diagrams, and operates only in the domain of science, it nevertheless represents an important milestone towards systems that can read and understand," the researchers stated in a newly published paper on ArXiv. "The momentum on this task has been remarkable, with accuracy moving from roughly 60% to over 90% in just three years," Though no diagrams were used for this particular task, the work as a whole integrates multiple AI-based technologies including natural language processing, information extraction, knowledge representation and reasoning, commonsense knowledge, and diagram understanding.
The Well-Grounded Rubyist [PDF] - Programmer Books
In this chapter, we'll explore Ruby's facilities for pattern matching and text processing, centering around the use of regular expressions. A regular expression in Ruby serves the same purposes it does in other languages: it specifies a pattern of characters, a pattern that may or may not correctly predict (that is, match) a given string. Pattern-match operations are used for conditional branching (match/no match), pinpointing substrings (parts of a string that match parts of the pattern), and various text-filtering techniques. Regular expressions in Ruby are objects. You send messages to a regular expression.
Pattern-Based Approach to the Workflow Satisfiability Problem with User-Independent Constraints
Karapetyan, Daniel, Parkes, Andrew J., Gutin, Gregory, Gagarin, Andrei
The fixed parameter tractable (FPT) approach is a powerful tool in tackling computationally hard problems.ย In this paper, we link FPT results to classic artificial intelligence (AI) techniques to show how they complement each other.ย Specifically, we consider the workflow satisfiability problem (WSP) which asks whether there exists an assignment of authorised users to the steps in a workflow specification, subject to certain constraints on the assignment.ย It was shown by Cohen et al. (JAIR 2014) that WSP restricted to the class of user-independent constraints (UI), covering many practical cases, admits FPT algorithms, i.e. can be solved in time exponential only in the number of steps k and polynomial in the number of users n.ย Since usually k << n in WSP, such FPT algorithms are of great practical interest.We present a new interpretation of the FPT nature of the WSP with UI constraints giving a decomposition of the problem into two levels.ย Exploiting this two-level split, we develop a new FPT algorithm that is by many orders of magnitude faster than the previous state-of-the-art WSP algorithm and also has only polynomial-space complexity.ย We also introduce new pseudo-Boolean (PB) and Constraint Satisfaction (CSP) formulations of the WSP with UI constraints which efficiently exploit this new decomposition of the problem and raise the novel issue of how to use general-purpose solvers to tackle FPT problems in a fashion that meets FPT efficiency expectations.ย In our computational study, we investigate, for the first time, the phase transition (PT) properties of the WSP, under a model for generation of random instances.ย We show how PT studies can be extended, in a novel fashion, to support empirical evaluation of scaling of FPT algorithms.
Heterogeneous Proxytypes Extended: Integrating Theory-like Representations and Mechanisms with Prototypes and Exemplars
The paper introduces an extension of the proposal according to which conceptual representations in cognitive agents should be intended as heterogeneous proxytypes . The main contribution of this paper is in that it details how to reconcile, under a heterogeneous representational perspective, different theories of typicality about conceptual representation and reasoning. In particular, it provides a novel theoretical hypothesis - as well as a novel categorization algorithm called DEL T A - showing how to integrate the representational and reasoning assumptions of the theory-theory of concepts with the those ascribed to the prototype and exemplars-based theories. Keywords: heterogeneous proxytypes, knowledge representation, cognitive agents, cognitive architectures, declarative memory. 1 Introduction The proposal of characterizing the representational system of cognitive artificial agents by considering conceptual representations as heterogeneous proxytypes was introduced in [17] 1 and has been recently employed and successfully tested in systems like DUAL-PECCS [21,20,22], later integrated with diverse cognitive architectures such as ACT - R [1], CLARION [32], SOAR [15] and V ector-LIDA [31]. The main contribution of this work is in that it offers a proposal to reconcile, under a heterogeneous representational perspective, not only prototype and exemplars based representations and reasoning procedures, but also the representational and reasoning assumptions ascribed to the so called theory-theory of concepts [27]. In doing so, the paper proposes a novel categorization algorithm, called DELTA (i.e.
Modelling Bushfire Evacuation Behaviours
Bushfires pose a significant threat to Australia's regional areas. To minimise risk and increase resilience, communities need robust evacuation strategies that account for people's likely behaviour both before and during a bushfire. Agent-based modelling (ABM) offers a practical way to simulate a range of bushfire evacuation scenarios. However, the ABM should reflect the diversity of possible human responses in a given community. The Belief-Desire-Intention (BDI) cognitive model captures behaviour in a compact representation that is understandable by domain experts. Within a BDI-ABM simulation, individual BDI agents can be assigned profiles that determine their likely behaviour. Over a population of agents their collective behaviour will characterise the community response. These profiles are drawn from existing human behaviour research and consultation with emergency services personnel and capture the expected behaviours of identified groups in the population, both prior to and during an evacuation. A realistic representation of each community can then be formed, and evacuation scenarios within the simulation can be used to explore the possible impact of population structure on outcomes. It is hoped that this will give an improved understanding of the risks associated with evacuation, and lead to tailored evacuation plans for each community to help them prepare for and respond to bushfire.