36997041
The Logic of Only Knowing as a Unified Framework for Non-Monotonic Reasoning
We propose to use the logic of only knowing (OL) by Levesque [10] as a unified framework that encompasses various non-monotonic formalisms and logic programming. OL is a modal logic which can be used to formalize an agent's introspective reasoning and to answer epistemic queries to databases. The OL logic allows one to formally express the statement “α is all I know” (in symbols, Oα) and to perform inferencing based on only-knowing, which is very useful for commonsense reasoning. Another nice thing about the OL logic is that it has a clear model-theoretic semantics and a simple proof theory, which is sound for the quantificational case, and both sound and complete for the prepositional case. We establish the relations between OL and various non-monotonic logics (such as default logic, circumscription) and logic programming, thus extending the existing works relating the OL logic with other non-monotonic reasoning formalisms (e.g., Levesque showed that autoepistemic logic can be embeded in OL). This is accomplished by finding the connection between OL and MBNF, the logic of Minimal Belief and Negation as Failure proposed by Lifschitz [12, 13], which is known to have close relationship with logic programming and other non-monotonic logics. Our results show that OL can be used as a unified framework to compare different non-monotonic formalisms based on the same domain.
39684197
A sound and complete proof theory for the generalized logic of only knowing
We present a sound and complete proof theory for the generalized logic of only knowing (GOL). The GOL logic is a modal logic proposed recently (Chen 1997) as a unified logical framework for non-monotonic reasoning, which extends the logic of only knowing (OL) of Levesque (1990), and covers the important notion of epistemic specification (Gelfond 1991, Gelfond and Przymusinska 1993) which is very useful for knowledge representation. The OL logic has been shown to have close connections with Lifschitz's minimal belief and negation as failure (Lifschitz 1994) and various other major non-monotonic formalisms. The GOL logic is more general and powerful than OL. The completeness result for the GOL proof theory establishes the theoretical foundation for answering queries in epistemic theories. This work is restricted to the propositional case only.
27866706
A New Method of Circumscribing Beliefs: The Propositional Case
We propose here a new notion of a minimal model for forming circumscription in belief-logic by incorporating the notion of minimal models in the prepositional logic. This results in a new circumscription operation for belief-formulas than the one considered in [4-6]. An important feature of the new circumscription operation is its close relationship with the circumscription of prepositional formulas. For instance, we have CIRC[Bp] = B(CIRC[p]), where p is a prepositional formula. We give several examples to show that the new notion of circumscription fits quite well with intuition.
31224210
The strong semantics for logic programs
Recently, the well-founded semantics of a logic programP has been strengthened to the well-founded semantics-by-case (WFC) and this in turn has been strengthened to the extended well-founded semantics (WFE). Both WFC(P) and WFE(P) have thelogical consequence property, namely, if an atomAj is true in the theory Th(P), thenAj is true in the semantics as well. However, neither WFC nor WFE has the GCWA property, i.e., if an atomAj is false in all minimal models ofP,Aj may not be false in WFC(P) (resp. WFE(P)). We extend the ideas in WFC and WFE to define a strong well-founded semantics WFS which has the GCWA property. The strong semantics WFS(P) is defined by combining GCWA with the notion ofderived rules. Here we use a new Type-III derived rules in addition to those used in WFC and WFE. The relationship between WFS and WFC is also clarified.
30548729
A Class of Stratified Programs in Autoepistemic Logic of Knowledge and Belief
Przymusinski proposed [11] AELB, the autoepistemic logic of knowledge and belief. The AELB logic is a very powerful and expressive formal system which isomorphically contains various major non-monotonic knowledge representation formalisms and major logic program semantics. Thus AELB can be used as a unifying framework for non-monotonic knowledge representation formalisms, which allows us to compare and better understand different formalizations of common-sense knowledge.
14245135
Automatic Correlation and Calibration of Noisy Sensor Readings Using Elite Genetic Algorithms
This paper explores an image processing application of optimization techniques which entails interpreting noisy sensor data. The application is a generalization of image correlation; we attempt to find the optimal gruence which matches two overlapping gray scale images corrupted with noise. Both tabu search and genetic algorithms are used to find the parameters which match the two images. A genetic algorithm approach using an elitist reproduction scheme is found to provide significantly superior results.
1345996
Locality aware dynamic load management for massively multiplayer games
Most massively multiplayer game servers employ static partitioning of their game world into distinct mini-worlds that are hosted on separate servers. This limits cross-server interactions between players, and exposes the division of the world to players. We have designed and implemented an architecture in which the partitioning of game regions across servers is transparent to players and interactions are not limited to objects in a single region or server. This allows a finer grain partitioning, which combined with a dynamic load management algorithm enables us to better handle transient crowding by adaptively dispersing or aggregating regions from servers in response to quality of service violations.Our load balancing algorithm is aware of the spatial locality in the virtual game world. Based on localized information, the algorithm balances the load and reduces the cross server communication, while avoiding frequent reassignment of regions. Our results show that locality aware load balancing reduces the average user response time by up to a factor of 6 compared to a global algorithm that does not consider spatial locality and by up to a factor of 8 compared to static partitioning.
17157033
On The Damage and Compensation of Privacy Leakage
A query on the distribution of a sensitive field within a selected population in a database can be submitted to the data center, and the answer to this query can leak private information, even though no identification information is provided. Inspired by decision theory, we present a quantitative model of the privacy protection problem in such a database query environment. In our model, the user information states are defined as classes of probability distributions on the set of possible confidential values. These states can be modified and refined by knowledge acquisition actions. The data confidentiality is guaranteed by ensuring that misusing private information is more costly than any possible gain.
14121852
Programming by demonstration - constructing task level plans in hybrid dynamic framework
This paper presents a novel approach to constructing a task level plan for an assembly task from demonstration. A hybrid dynamic system is chosen as an attractive way to model assembly tasks. We propose a framework where the mappings required within the hybrid dynamic system model are extracted from a demonstration. We extract the event path planner mapping, which determines a task level plan. Demonstrated paths are broken down into their base elements, called transitions. A path plan is then constructed from transitions that were well demonstrated. We test the approach by having a robot execute an assembly task using constructed task plans. The framework produces excellent results because: 1) the robot can perform selected paths better than when it simply copies the demonstrator, and 2) it allows flexible path selection so the robot can be given a disposition in how it executes the task.
13034661
A probabilistic approach to fault-tolerant routing algorithm on mesh networks
In this paper, we propose a novel and efficient fault tolerant routing algorithm for mesh networks based on the concept of k-submesh without virtual channels and not sacrifice non-faulty nodes. Our algorithm is distributed and local information based. Due to the fact that our algorithm is designed based on k-submesh structure, we apply probabilistic analysis on the fault tolerance of our routing algorithm. Suppose that each node has an independent failure probability, we derive the probability that our routing algorithm successfully returns a fault-free routing path. For example, we formally prove that as long as the node failure probability is bounded by 0.35%, our routing algorithm succeeds in finding a fault-free routing path with high probability of 99% on mesh networks with 250000 nodes. Our algorithm runs in liner time and simulation results show that the length of the routing path constructed by our algorithm are very close to the optimal length.
16627993
Increased display size and resolution improve task performance in Information-Rich Virtual Environments
Physically large-size high-resolution displays have been widely applied in various fields. There is a lack of research, however, that demonstrates empirically how users benefit from the increased size and resolution afforded by emerging technologies. We designed a controlled experiment to evaluate the individual and combined effects of display size and resolution on task performance in an Information-Rich Virtual Environment (IRVE). We also explored how a wayfinding aid would facilitate spatial information acquisition and mental map construction when users worked with various displays. We found that users were most effective at performing IRVE search and comparison tasks on large high-resolution displays. In addition, users working with large displays became less reliant on wayfinding aids to form spatial knowledge. We discuss the impact of these results on the design and presentation of IRVEs, the choice of displays for particular applications, and future work to extend our findings.