Anonymity and Information Hiding in Multiagent Systems

We provide a framework for reasoning about information-hiding requirements in multiagent systems and for reasoning about anonymity in particular. Our framework employs the modal logic of knowledge within the context of the runs and systems framework, much in the spirit of our earlier work on secrecy [Halpern and O'Neill 2002]. We give several definitions of anonymity with respect to agents, actions, and observers in multiagent systems, and we relate our definitions of anonymity to other definitions of information hiding, such as secrecy. We also give probabilistic definitions of anonymity that are able to quantify an observer s uncertainty about the state of the system. Finally, we relate our definitions of anonymity to other formalizations of anonymity and information hiding, including definitions of anonymity in the process algebra CSP and definitions of information hiding using function views.Comment: Replacement. 36 pages. Full version of CSFW '03 paper, submitted to JCS. Made substantial changes to Section 6; added references throughou

Symbolic Synthesis of Knowledge-based Program Implementations with Synchronous Semantics

This paper deals with the automated synthesis of implementations of knowledge-based programs with respect to two synchronous semantics (clock and synchronous perfect recall). An approach to the synthesis problem based on the use of symbolic representations is described. The method has been implemented as an extension to the model checker MCK. Two applications of the implemented synthesis system are presented: the muddy children puzzle (where performance is compared to an explicit state method for a related problem implemented in the model checker DEMO), and a knowledge-based program for a dynamic leader election problem in a ring of processes

A Taxonomy for and Analysis of Anonymous Communications Networks

Any entity operating in cyberspace is susceptible to debilitating attacks. With cyber attacks intended to gather intelligence and disrupt communications rapidly replacing the threat of conventional and nuclear attacks, a new age of warfare is at hand. In 2003, the United States acknowledged that the speed and anonymity of cyber attacks makes distinguishing among the actions of terrorists, criminals, and nation states difficult. Even President Obama’s Cybersecurity Chief-elect recognizes the challenge of increasingly sophisticated cyber attacks. Now through April 2009, the White House is reviewing federal cyber initiatives to protect US citizen privacy rights. Indeed, the rising quantity and ubiquity of new surveillance technologies in cyberspace enables instant, undetectable, and unsolicited information collection about entities. Hence, anonymity and privacy are becoming increasingly important issues. Anonymization enables entities to protect their data and systems from a diverse set of cyber attacks and preserves privacy. This research provides a systematic analysis of anonymity degradation, preservation and elimination in cyberspace to enhance the security of information assets. This includes discovery/obfuscation of identities and actions of/from potential adversaries. First, novel taxonomies are developed for classifying and comparing well-established anonymous networking protocols. These expand the classical definition of anonymity and capture the peer-to-peer and mobile ad hoc anonymous protocol family relationships. Second, a unique synthesis of state-of-the-art anonymity metrics is provided. This significantly aids an entity’s ability to reliably measure changing anonymity levels; thereby, increasing their ability to defend against cyber attacks. Finally, a novel epistemic-based mathematical model is created to characterize how an adversary reasons with knowledge to degrade anonymity. This offers multiple anonymity property representations and well-defined logical proofs to ensure the accuracy and correctness of current and future anonymous network protocol design

An Ontology based Text-to-Picture Multimedia m-Learning System

Multimedia Text-to-Picture is the process of building mental representation from words associated with images. From the research aspect, multimedia instructional message items are illustrations of material using words and pictures that are designed to promote user realization. Illustrations can be presented in a static form such as images, symbols, icons, figures, tables, charts, and maps; or in a dynamic form such as animation, or video clips. Due to the intuitiveness and vividness of visual illustration, many text to picture systems have been proposed in the literature like, Word2Image, Chat with Illustrations, and many others as discussed in the literature review chapter of this thesis. However, we found that some common limitations exist in these systems, especially for the presented images. In fact, the retrieved materials are not fully suitable for educational purposes. Many of them are not context-based and didn’t take into consideration the need of learners (i.e., general purpose images). Manually finding the required pedagogic images to illustrate educational content for learners is inefficient and requires huge efforts, which is a very challenging task. In addition, the available learning systems that mine text based on keywords or sentences selection provide incomplete pedagogic illustrations. This is because words and their semantically related terms are not considered during the process of finding illustrations. In this dissertation, we propose new approaches based on the semantic conceptual graph and semantically distributed weights to mine optimal illustrations that match Arabic text in the children’s story domain. We combine these approaches with best keywords and sentences selection algorithms, in order to improve the retrieval of images matching the Arabic text. Our findings show significant improvements in modelling Arabic vocabulary with the most meaningful images and best coverage of the domain in discourse. We also develop a mobile Text-to-Picture System that has two novel features, which are (1) a conceptual graph visualization (CGV) and (2) a visual illustrative assessment. The CGV shows the relationship between terms associated with a picture. It enables the learners to discover the semantic links between Arabic terms and improve their understanding of Arabic vocabulary. The assessment component allows the instructor to automatically follow up the performance of learners. Our experiments demonstrate the efficiency of our multimedia text-to-picture system in enhancing the learners’ knowledge and boost their comprehension of Arabic vocabulary

Data Recovery at 41MI96 in Mills County, Texas

Prehistoric site 41MI96 in Mills County, Texas was subjected to archeological data recovery excavations by staff archeologists from the Archeological Studies Program of the Texas Department of Transportation (TxDOT) in May 1999. This work followed an initial environmental review by TxDOT personnel that concluded that a proposed bridge replacement and associated realignment of a county road (CSJ: 0923- 23-011) had a high probability to impact previously unrecorded archeological sites. Subsequently, an archeological impact evaluation was conducted by TxDOT staff archeologists, under the direction of Dr. G. Lain Ellis. TxDOT investigations were conducted under Texas Antiquities Committee Permit No. 2193 to perform data recovery efforts at 41MI96 prior to development impacts. In 2012, TRC Environmental Corporation (TRC) of Austin was contracted by the Environmental Affairs Division of TxDOT through Work Authorization 57-109SA003 to conduct analysis on the recovered remains and complete a technical report of TxDOT’s field investigations and TRC’s laboratory findings in fulfillment of TxDOTs’ Antiquities permit. Data recovery excavations consisted of the excavation of four mechanical trenches across two creek terraces (T1 and T2) and hand-excavations in two small blocks (Blocks 1 and 2) within the TxDOT right-of-way on the northwestern side of the project area. Hand-excavations in both blocks were initiated to target newly discovered burned rock concentrations encountered in the bottom of backhoe scrapings. A total 5.5 m3 of manualexcavation was completed, which was comprised of 16 total 1-by-1 m units, 11 in Block 1, and 5 in Block 2. Cultural materials were dominated by ca. 602 burned rocks and 2,846 pieces of lithic debitage, 89 informal and formal tools, but lacked diagnostic artifacts and faunal material. Six small, intact burned rock features were identified in Block 1 and were the focus of laboratory analyses. The scattered burned rocks and debitage from Block 2 were only tabulated and discussed in a general way, as TxDOT personnel believed they were in mixed context. The six small burned rock features ranged in size from 33 to 100 cm in diameter and represented four intact heating elements (two with basins and two without), plus two small burned rock discard piles. Radiocarbon dating of organic residues in nine burned rocks from five intact features indicates multiple occupations over a span of roughly 700 years from 820 to 1450 B.P. (cal A.D. 560 to 1270). The lack of recorded depth measurements for cultural materials, combined with limited sediment deposition between the successive occupations, prevented isolation of individual occupational episodes. The lack of discernible vertical separation in the prehistoric occupations reflects slow soil aggregation during this period, likely lengthy surface exposure and possible erosion between events, and soil conditions which may also account for a near absence of charcoal and other organic materials such as vertebrate remains. Four technical analyses (radiocarbon dating, starch grain, lipid residue, and high-powered usewear) focused on a limited suite of chipped stone tools, associated lithic debitage, and burned rocks collected from five of the six intact features in Block 1 in the T2 terrace. Starch grain analysis on fragments of 20 burned rocks from five features and 20 chipped stone tools from around the features in Block 1 yielded positive results from 47.5 percent of the specimens. Of considerable interest is the documentation, in addition to multiple grass species, of grains of the tropical cultigen maize (Zea mays) on two burned rocks each, from Features 2 and 3, plus on two edge-modified tools in the vicinity of those two features. One specific burned rock with a gelatinized maize starch grain on it was directly AMS dated to 980 ± 30 B.P. or cal A.D. 1020 to 1150. Some identified maize starch grains had been damaged through grinding, heating, and/or boiling, evidence of processing as a food resource. This indicates use of maize as a food resource in central Texas a number of centuries earlier than previously suspected. Lipid residue analysis on portions of the same 20 burned rocks from those five features yielded residues in 100 percent of the samples. The results indicate that both plant and animal products were present on all the rocks, with large herbivore lipids (likely bison or deer) present on at least one rock, and oily seed lipids present on at least three rocks. Residues from conifer wood products, here likely juniper trees, were present on 60 percent of the rocks, and indicate at least one specific wood species used to heat the rocks. High-powered microscopic use-wear analyses on 15 chert tools (11 edge-modified flakes, 2 biface fragments, and 2 complete choppers) revealed their use in processing wood, plants, bone, and hide as well as unspecified soft and hard materials. The sparse frequency of formal chipped stone tools likely reflects the limited area investigated and also the possibility that these occupations reflect low-intensity and short-term camps that focused on preparing and cooking a few food resources in heating facilities and the manipulation of other perishable resources. The lipid and starch analyses of the burned rocks provides important information concerning the resources cooked by the rocks in these small burned rock features, most significantly the presence of maize and wild native grasses. These resources would have gone unidentified without these specialized analyses. Continued use of these two analytical techniques on suites of burned rocks from other features/sites in and around central Texas will provide an empirical basis for identifying changes in subsistence patterns over time and across geographical space. It is also notable that direct radiocarbon dating of organic residues contained within the porous sandstone burned rocks here has succeeded in providing satisfactory chronological control for the features and site, strongly indicating that this technique can be beneficially employed in the future in cases where other organics such as wood charcoal, charred seeds/nuts, and/or bone are unavailable for absolute dating. In 1999 the Texas Historical Commission accepted TxDOT’s field investigations as sufficient and concurred with TxDOT’s recommendation that no further work was necessary under Texas Antiquities Committee Permit No. 2193. Parts of site 41MI96 outside the current TxDOT right-of-way have not been fully evaluated. Based on the present findings and the excavated intact features in Block 1, it appears that potentially eligible deposits may be present beyond the current right-of-way. If TxDOT further expands this county road, it is recommended that those areas at 41MI96 be evaluated prior to surface modifications related to that project

A Framework for the Organization and Discovery of Information Resources in a WWW Environment Using Association, Classification and Deduction

The Semantic Web is envisioned as a next-generation WWW environment in which information is given well-defined meaning. Although the standards for the Semantic Web are being established, it is as yet unclear how the Semantic Web will allow information resources to be effectively organized and discovered in an automated fashion. This dissertation research explores the organization and discovery of resources for the Semantic Web. It assumes that resources on the Semantic Web will be retrieved based on metadata and ontologies that will provide an effective basis for automated deduction. An integrated deduction system based on the Resource Description Framework (RDF), the DARPA Agent Markup Language (DAML) and description logic (DL) was built. A case study was conducted to study the system effectiveness in retrieving resources in a large Web resource collection. The results showed that deduction has an overall positive impact on the retrieval of the collection over the defined queries. The greatest positive impact occurred when precision was perfect with no decrease in recall. The sensitivity analysis was conducted over properties of resources, subject categories, query expressions and relevance judgment in observing their relationships with the retrieval performance. The results highlight both the potentials and various issues in applying deduction over metadata and ontologies. Further investigation will be required for additional improvement. The factors that can contribute to degraded performance were identified and addressed. Some guidelines were developed based on the lessons learned from the case study for the development of Semantic Web data and systems

Arrows for knowledge-based circuits

Knowledge-based programs (KBPs) are a formalism for directly relating agents' knowledge and behaviour in a way that has proven useful for specifying distributed systems. Here we present a scheme for compiling KBPs to executable automata in finite environments with a proof of correctness in Isabelle/HOL. We use Arrows, a functional programming abstraction, to structure a prototype domain-specific synchronous language embedded in Haskell. By adapting our compilation scheme to use symbolic representations we can apply it to several examples of reasonable size

how reproduction in captivity can help an endangered species

openPartendo dalla biologia della specie del giaguaro, focalizzandomi sulla sua riproduzione in natura, faccio una comparazione su come può avvenire in cattività. Di seguito parlo della esperienza che ho avuto durante il mio tirocinio facendo un focus sulle riproduzioni di giaguari avvenute nel centro. Per concludere analizzo come la riproduzione dei giaguari in cattività possa aiutare a far crescere la popolazione in libertà in Ecuador.Starting with the biology of the jaguar species, focusing on its reproduction in the wild, I'll make a comparison on how it can take place in captivity. Following this, I'll talk about the experience I had during my internship with a focus on the jaguars' breeding history happened at the rescue centre. To conclude I analyse how the reproduction of jaguars in captivity can help to grow the population in the wild in Ecuador