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Preference Handling - An Introductory Tutorial

AI Magazine

Early work in AI focused on the notion of a goal--an explicit target that must be achieved--and this paradigm is still dominant in AI problem solving. But as application domains become more complex and realistic, it is apparent that the dichotomic notion of a goal, while adequate for certain puzzles, is too crude in general. The problem is that in many contemporary application domains, for example, information retrieval from large databases or the web, or planning in complex domains, the user has little knowledge about the set of possible solutions or feasible items, and what she or he typically seeks is the best that's out there. But since the user does not know what is the best achievable plan or the best available document or product, he or she typically cannot characterize it or its properties specifically. As a result, the user will end up either asking for an unachievable goal, getting no solution in response, or asking for too little, obtaining a solution that can be substantially improved. Of course, the user can gradually adjust the stated goals. This, however, is not a very appealing mode of interaction because the space of alternative solutions in such applications can be combinatorially huge, or even infinite. Moreover, such incremental goal refinement is simply infeasible when the goal must be supplied offline, as in the case of autonomous agents (whether on the web or on Mars).


Using Game Theory for Los Angeles Airport Security

AI Magazine

Security at major locations of economic or political importance is a key concern around the world, particularly given the threat of terrorism. Limited security resources prevent full security coverage at all times, which allows adversaries to observe and exploit patterns in selective patrolling or monitoring, e.g. they can plan an attack avoiding existing patrols. Hence, randomized patrolling or monitoring is important, but randomization must provide distinct weights to different actions based on their complex costs and benefits. To this end, this paper describes a promising transition of the latest in multi-agent algorithms into a deployed application. In particular, it describes a software assistant agent called ARMOR (Assistant for Randomized Monitoring over Routes) that casts this patrolling/monitoring problem as a Bayesian Stackelberg game, allowing the agent to appropriately weigh the different actions in randomization, as well as uncertainty over adversary types. ARMOR combines two key features: (i) It uses the fastest known solver for Bayesian Stackelberg games called DOBSS, where the dominant mixed strategies enable randomization; (ii) Its mixed-initiative based interface allows users to occasionally adjust or override the automated schedule based on their local constraints. ARMOR has been successfully deployed since August 2007 at the Los Angeles International Airport (LAX) to randomize checkpoints on the roadways entering the airport and canine patrol routes within the airport terminals. This paper examines the information, design choices, challenges, and evaluation that went into designing ARMOR.


Agents, Bodies, Constraints, Dynamics, and Evolution

AI Magazine

The theme of this article is the dynamics of evolution of agents. That theme is applied to the evolution of constraint satisfaction, of agents themselves, of our models of agents, of artificial intelligence and, finally, of the Association for the Advancement of Artificial Intelligence (AAAI). The overall thesis is that constraint satisfaction is central to proactive and responsive intelligent behavior.


Switcher-random-walks: a cognitive-inspired mechanism for network exploration

arXiv.org Artificial Intelligence

Semantic memory is the subsystem of human memory that stores knowledge of concepts or meanings, as opposed to life specific experiences. The organization of concepts within semantic memory can be understood as a semantic network, where the concepts (nodes) are associated (linked) to others depending on perceptions, similarities, etc. Lexical access is the complementary part of this system and allows the retrieval of such organized knowledge. While conceptual information is stored under certain underlying organization (and thus gives rise to a specific topology), it is crucial to have an accurate access to any of the information units, e.g. the concepts, for efficiently retrieving semantic information for real-time needings. An example of an information retrieval process occurs in verbal fluency tasks, and it is known to involve two different mechanisms: -clustering-, or generating words within a subcategory, and, when a subcategory is exhausted, -switching- to a new subcategory. We extended this approach to random-walking on a network (clustering) in combination to jumping (switching) to any node with certain probability and derived its analytical expression based on Markov chains. Results show that this dual mechanism contributes to optimize the exploration of different network models in terms of the mean first passage time. Additionally, this cognitive inspired dual mechanism opens a new framework to better understand and evaluate exploration, propagation and transport phenomena in other complex systems where switching-like phenomena are feasible.


Designing a GUI for Proofs - Evaluation of an HCI Experiment

arXiv.org Artificial Intelligence

Human-computer interaction (HCI) is the interdisciplinary study of interaction between people (users) and computers. Its main goal is making computers more user-friendly and easier to use. HCI is concerned with methodologies and processes for designing interfaces, with methods for implementing interfaces, with techniques for evaluating and comparing interfaces, with developing new interfaces and interaction techniques and with developing descriptive and predictive models and theories of interaction [9]. More often than not, user interfaces for theorem provers are developed as a mere add-on to the main proving engine. The result is an interaction design suitable for proof experts only.


Comment on "Language Trees and Zipping" arXiv:cond-mat/0108530

arXiv.org Artificial Intelligence

Departmant of Chinese Literature and Language Anhui University Hefei Anhui 230039 China (Dated: February 12, 2018) every encoding has priori information if the encoding represents any semantic information of the un-verse or object.Encoding means mappingfrom the un-verseto thestringor strings of digits. The semantic here is used in the model-theoretic sense or denotation of the object.if Several statements that Benedetto et al.make in their Letter [1, 2]are not certainly true.First,We claim a statement that Benedetto et al.. make in their Letter and their reply [1, 2]has mixed strings of symbols with the objects or models the strings denote.In another word,strings of symbols are different from the object or model the strings denote except when the strings only denote themselves.Moreover,a statement of the comment on the Letter by Dmitry V. Khmelev et al.is inaccurate [3].That is,"Notice that the language tree (LT) diagram [1] does not include the Russian language (Slavic family of Indo-European family of languages: 288 10 Our computations show that once Russian is included, it does not cluster with the other members of the Slavic group. Obviously, certain Cyrillic alphabet based languages were left out of the study, which improves results significantly and shows that a priori information about the alphabet is being taken advantage of to achieve the results outlined in their Letter.". String of symbols and symbol may self-refer or refer to other object.When It refer to or denote another object,we say the object is model of the string of symbols or meaning (semantics) of the string of symbols [4, 5].The string of symbols represents the object or the model.Obviously when It refer to or denote Itself,the meaning or model and the symbol or string of symbols are the same.The alphabet or text(string of symbols) are not language.They are symbols or strings of symbols that just record the language Clearly,every encoding has priori information if the encoding represents any semantic information of the unverse or object.Encoding means mapping from the unverse to the string or strings of digits.


Decomposition, Reformulation, and Diving in University Course Timetabling

arXiv.org Artificial Intelligence

In many real-life optimisation problems, there are multiple interacting components in a solution. For example, different components might specify assignments to different kinds of resource. Often, each component is associated with different sets of soft constraints, and so with different measures of soft constraint violation. The goal is then to minimise a linear combination of such measures. This paper studies an approach to such problems, which can be thought of as multiphase exploitation of multiple objective-/value-restricted submodels. In this approach, only one computationally difficult component of a problem and the associated subset of objectives is considered at first. This produces partial solutions, which define interesting neighbourhoods in the search space of the complete problem. Often, it is possible to pick the initial component so that variable aggregation can be performed at the first stage, and the neighbourhoods to be explored next are guaranteed to contain feasible solutions. Using integer programming, it is then easy to implement heuristics producing solutions with bounds on their quality. Our study is performed on a university course timetabling problem used in the 2007 International Timetabling Competition, also known as the Udine Course Timetabling Problem. In the proposed heuristic, an objective-restricted neighbourhood generator produces assignments of periods to events, with decreasing numbers of violations of two period-related soft constraints. Those are relaxed into assignments of events to days, which define neighbourhoods that are easier to search with respect to all four soft constraints. Integer programming formulations for all subproblems are given and evaluated using ILOG CPLEX 11. The wider applicability of this approach is analysed and discussed.


Efficiently Learning a Detection Cascade with Sparse Eigenvectors

arXiv.org Artificial Intelligence

In this work, we first show that feature selection methods other than boosting can also be used for training an efficient object detector. In particular, we introduce Greedy Sparse Linear Discriminant Analysis (GSLDA) \cite{Moghaddam2007Fast} for its conceptual simplicity and computational efficiency; and slightly better detection performance is achieved compared with \cite{Viola2004Robust}. Moreover, we propose a new technique, termed Boosted Greedy Sparse Linear Discriminant Analysis (BGSLDA), to efficiently train a detection cascade. BGSLDA exploits the sample re-weighting property of boosting and the class-separability criterion of GSLDA.


Mechanisms for Making Crowds Truthful

Journal of Artificial Intelligence Research

We consider schemes for obtaining truthful reports on a common but hidden signal from large groups of rational, self-interested agents. One example are online feedback mechanisms, where users provide observations about the quality of a product or service so that other users can have an accurate idea of what quality they can expect. However, (i) providing such feedback is costly, and (ii) there are many motivations for providing incorrect feedback. Both problems can be addressed by reward schemes which (i) cover the cost of obtaining and reporting feedback, and (ii) maximize the expected reward of a rational agent who reports truthfully. We address the design of such incentive-compatible rewards for feedback generated in environments with pure adverse selection. Here, the correlation between the true knowledge of an agent and her beliefs regarding the likelihoods of reports of other agents can be exploited to make honest reporting a Nash equilibrium. In this paper we extend existing methods for designing incentive-compatible rewards by also considering collusion. We analyze different scenarios, where, for example, some or all of the agents collude. For each scenario we investigate whether a collusion-resistant, incentive-compatible reward scheme exists, and use automated mechanism design to specify an algorithm for deriving an efficient reward mechanism.


The Benefit of Group Sparsity

arXiv.org Machine Learning

This paper develops a theory for group Lasso using a concept called strong group sparsity. Our result shows that group Lasso is superior to standard Lasso for strongly group-sparse signals. This provides a convincing theoretical justification for using group sparse regularization when the underlying group structure is consistent with the data. Moreover, the theory predicts some limitations of the group Lasso formulation that are confirmed by simulation studies.