The notion of time is ubiquitous in any activity that requires intelligence. In particular, several important notions like change, causality, action are described in terms of time. Therefore, the representation of time and reasoning about time is of crucial importance for many Artificial Intelligence systems. Specifically during the last 10 years, it has been attracting the attention of many AI researchers. In this survey, the results of this work are analysed. Firstly, Temporal Reasoning is defined. Then, the most important representational issues which determine a Temporal Reasoning approach are introduced: the logical form on which the approach is based, the ontology (the units taken as primitives, the temporal relations, the algorithms that have been developed,. . . ) and the concepts related with reasoning about action (the representation of change, causality, action,. . . ). For each issue the different choices in the literature are discussed. 1 Introduction The notion of time i...

In this paper we address the problem of scalability in temporal reasoning. In particular, new algorithms for efficiently managing large sets of relations in the Point Algebra are provided. Our representation of time is based on timegraphs, graphs partitioned into a set of chains on which the search is supported by a rnetagraph data structure. The approach is an extension of the time representation proposed by Schubert, Taugher and Miller in the context of story comprehension. The algorithms presented in this work concern the construction of a timegraph from a given set of relations and are implemented in a temporal reasoning system called TG-II. Experimental results show that our approach is very efficient, especially when the given relations admit representation as a collection of chains connected by relatively few cross-chain links. 1

Reasoning about temporal information is an important task in many areas of Artificial Intelligence. In this paper we address the problem of scalability in temporal reasoning by providing a collection of new algorithms for efficiently managing large sets of qualitative temporal relations. We focus on the class of relations forming the Point Algebra (PA-relations) and on a major extension to include binary disjunctions of PA-relations (PA-disjunctions). Such disjunctions add a great deal of expressive power, including the ability to stipulate disjointness of temporal intervals, which is important in planning applications. Our representation of time is based on timegraphs, graphs partitioned into a set of chains on which the search is supported by a metagraph data structure. The approach is an extension of the time representation proposed by Schubert, Taugher and Miller in the context of story comprehension. The algorithms herein enable construction of a timegraph from a given set of PA-r...

Acknowledgements: The development of NeBIC theory has benefited greatly from the detailed guidance of the editor, associate editor, and reviewers. I also wish to thank research associate Michael Williams and Arvin Sayam for their valuable assistance and healthy debate in maturing the ideas presented here. NeBIC: A Dynamic Capabilities Theory for Assessing Net-enablement We propose the Net-enabled Business Innovation Cycle as an applied dynamic capabilities theory for measuring, predicting, and understanding a firm’s ability to create customer value through the business use of digital networks. The theory incorporates both a variance and process view of netenabled business innovation. It identifies four sequenced constructs: Choosing new IT, Matching with Economic Opportunities, Executing Business Innovation for Growth, and Assessing Customer Value, along with the processes and events that inter-relate them as a cycle. The sequence of these theorized relationships for net-enablement asserts that choosing IT precedes rather than aligns with corporate strategy. The theory offers a logically consistent and falsifiable basis for grounding research programs on metrics of net-enabled business innovation. NeBIC Page 1 1

We analyze the problem of computing the minimal labels for a network of temporal relations in the Point Algebra. van Beek proposes an algorithm for accomplishing this task which takes O(max(n 3 ; n 2 \Delta m)) time (for n points and m 6=-relations). We show that the proof of the correctness of this algorithm given by van Beek and Cohen is faulty, and we provide a new proof showing that the algorithm is indeed correct. Keywords: temporal reasoning, Point Algebra, constraint networks, reasoning with inequations The work of the first author was carried out in part during a visit at the Computer Science Department of the University of Rochester (NY) supported by the Italian National Research Council (CNR), and in part at IRST in the context of the MAIA project and CNR projects "Sistemi Informatici e Calcolo Parallelo" and "Pianificazione Automatica". The second author was supported by Rome Lab Contract F30602-91-C-0010. 1 Introduction The Interval Algebra (IA) (Allen 1983) and t...

The maintenance of semantic integrity has been recognized as a cornerstone issue for the development of databases and knowledge bases alike. Despite the extensive research conducted during the last two decades, semantic integrity maintenance has yet to become a practical technology. Furthermore, the need for modeling evolving domains has given rise to challenging research issues relating to the incorporation of time in knowledge bases. In this thesis, we study the problem of maintaining the integrity of temporal deductive knowledge bases. We argue that existing approaches in either temporal or deductive databases do not address the problem in a satisfactory manner, nor do they deal with all the issues involved in a unified framework. At first, we propose an assertion language that permits us to express different types of temporal assertions that are not expressible in other formalisms. We define the notion of temporal constraint satisfaction in a bitemporal context. We then follow two ...

We address the problems of determining consistency and of finding a solution for sets of 3-point relations expressing exclusion of a point from an interval, and for sets of 4-point relations expressing interval disjointness. Availability of these relations is an important requirement for dealing with the sorts of temporal constraints encountered in many AI applications such as plan reasoning. We prove that consistency testing is NP-complete and finding a solution is NP-hard. Keywords: temporal reasoning, complexity of reasoning, planning, reasoning with disjunctions The work of the first author was carried out in part during a visit at the Computer Science Department of the University of Rochester (NY) supported by the Italian National Research Council (CNR), and in part at IRST in the context of the MAIA project and CNR projects "Sistemi Informatici e Calcolo Parallelo" and "Pianificazione Automatica". The second author was supported by Rome Lab Contract F30602-91-C-0010. 1 Introd...

In this paper we propose a new method for evaluating systems that extract temporal information from text. It uses temporal closure 1 to reward relations that are equivalent but distinct. Our metric measures the overall performance of systems with a single score, making comparison between different systems straightforward. Our approach is easy to implement, intuitive, accurate, scalable and computationally inexpensive. 1

Opportunity exploitation is a necessary step in creating a successful business in the entrepreneurial process, yet there has been little conceptual and empirical development of this issue in the literature. This study examines the decisions of entrepreneurs to begin exploiting business opportunitiesfrom a resource-based viewv. Our analysis of a sample of entrepreneurs whose businesses are located in incubators suggests that entrepreneurs are more likely to exploit opportunities when they perceive more knowledge of customer demand for the new product, more fully developed necessary technologies, greater managerial capability and greater stakeholder support. Moreover thefindings of this study shed a light on a less emplhasized aspect of the resource-based view: the new product's anticipated lead time acts as an enhancing moderator in entrepreneurs ' exploitation decision policies. bInplicationsforfuture research on opportunity exploitation are discussed. © 2003 Elsevier Itnc. All rights reserved. Entrepreneurship involves phenomena and processes related to discovering, evaluating, and exploiting opportunities to create future goods and services (Shane & Venkataraman, 2000). The outcome of this process is new products or services or both. Newness, however,

Most of AI research on temporal reasoning has been devoted to either exploring constraint-based temporal deduction techniques or investigating diverse logics extended with time. Nevertheless the formal study of deductive systems for such temporal extended logics has received little attention. This paper presents a general framework for temporal reasoning in knowledge-based systems resulting from embedding a temporal reasoner into a general calculus. From a representational point of view it is based on the notions of temporal token and temporal constraint. The logic is formally defined as a particular many-sorted predicate calculus and provided with an complete and sound inference system composed of non-temporal and temporal inference rules. Moreover, a deductive procedure is presented and analyzed. It is a general forward chaining algorithm for which soundness and completeness are guaranteed. 1 Introduction Representation and reasoning about time is relevant to many AI areas like pred...