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Adding modal operators to the action language A
Proceedings of the International Workshop on Non-Monotonic Reasoning (NMR-04) in Whistler, BC, 2004. The action language A is a simple high-level language for describing transition systems. In this paper, we extend the action language A by allowing a unary modal operator in the underlying propositional logic. The extended language requires very little new machinery, and it is suitable for describing transitions between Kripke structures. We consider some formal restrictions on action descriptions that preserve natural classes of Kripke structures, and we prove that the modal epistemic extension of A naturally subsumes related approaches to reasoning about knowledge. We conclude with some plans for future work. Introduction The action language A is a simple high-level language for reasoning about the effects of actions (Gelfond & Lifschitz 1993). The basic language is suitable only for simple action domains, but it has been extended several times to address a wide range of problems (Baral & Gelfond 1997; Baral, Gelfond, & Provetti 1997). In this paper, we suggest that it is possible to increase the representational power of A without changing the action language itself. Instead, we look at extending the underlying propositional logic by adding modal operators. We consider the expressive power of the modal extension, and compare the framework with related work on epistemic extensions of A., Conference paper, Published.
Application of hygrothermal analyses to optimize exterior wall design
Proceedings of 2nd International Conference on Research in Building Physics: 14 September 2003, Leuven, Belgium. The design of exterior walls in a building envelope for optimum moisture management is a challenging task. Many conventional methods or local practice guidelines are available for this purpose, based primarily on regional traditions and with limited performance assessment records. In recent years, new wall systems and unconventional materials have been introduced in every part of North America for reasons such as aesthetic appeal, cost-effectiveness etc. However, neither the long-term moisture management performance of these new wall systems nor the uses of unconventional materials have been assessed rigorously. The primary reason for this lack of such assessment is the absence of a design-oriented technical routine toperform the task. Recent studies at the Institute for Research in Construction (IRC) / National Research Council (NRC) of Canada, show that such an assessment is possible with the use of an advanced hygrothermal modelling tool, such as hygIRC, developed in-house at IRC. This paper presents results from hygrothermal modelling and discussion on walls with the four different cladding systems: stucco, exterior insulated finish systems (EIFS), masonry and siding. These walls were virtually exposed to several North American climates. Their hygrothermal responses were assessed with a novel indicator, called the RHT index, which is derived from relative humidity and temperature. The results and discussion presented in this paper clearly show the need and usefulness of an integrated design methodology for the moisture management of exterior wall systems that can help to optimise various design considerations., Conference paper, Published. A version of this document is published in: Research in Building Physics, Leuven, Belgium, Sept. 14-18, 2003, pp. 417-426.
Application of modeling tool to assess moisture and thermal performance of retrofitted wall assemblies
Proceedings of CIB World Building Congress 2004: 02 May 2004, Toronto, Ontario. As the stock of buildings in Canada ages, it is expected that there will be an increase in building envelope rehabilitation work. Such activities represent an ideal opportunity to add insulation and reduce air leakage to improve energy efficiency and building envelope durability. However, there is very little information available on how to assess the moisture and thermal (i.e. energy) performance of retrofitted building envelope assemblies and select the optimum retrofit options that will maximize the energy efficiency without compromising the long-term moisture performance of the retrofitted building envelopes. This paper depicts selected results from a study that has used a two-dimensional hygrothermal simulation tool, hygIRC-2D, to assess thermal and moisture performance of retrofitted masonry walls used in high-rise construction. The performance analyses of three basic (i.e. base case) masonry wall systems (Brick Veneer - Steel Stud, Brick Veneer - Concrete Masonry, and Precast Concrete Panels - Steel Stud) with four retrofit options, located in the National Capital Region (Ottawa-Gatineau) of Canada, are presented in this paper. The results from the simulations indicate that hygrothermal simulation tools can be used to evaluate the thermal and moisture performance of various wall systems and associated retrofit options. Simulations results also indicate that with specific retrofit options the energy performance of the wall system can be improved significantly without compromising the moisture response of the wall by adding insulation and reducing air-leakage in the wall assembly. However, heat or energy loss through the wall system is directly proportional to the air-leakage characteristics of the wall system. In general, based on the results presented in this paper, it can be concluded that use of a hygrothermal simulation tool can help to identify potentially problematic retrofit strategies while more promising measures can be advanced for additional assessment through full-scale laboratory testing or field demonstration., Conference paper, Published. A version of this document is published in: CIB World Building Congress 2004, Toronto, Ontario, May 2-7, 2004, pp. 1-10.
Arbitrary announcements in propositional belief revision
Proceedings of the International Workshop on Defeasible and Ampliative Reasoning (DARe-15) in Buenos Aires, Argentina, July 27, 2015. Public announcements cause each agent in a group to modify their beliefs to incorporate some new piece of information, while simultaneously being aware that all other agents are doing the same. Given some fixed goal formula, it is natural to ask if there exists an announcement that will make the formula true in a multi-agent context. This problem is known to be undecidable in a general modal setting, where the presence of nested beliefs can lead to complex dynamics. In this paper, we consider not necessarily truthful public announcements in the setting of propositional belief revision. We are given a goal formula for each agent, and we are interested in finding a single announcement that will make each agent believe the corresponding goal following AGM-style belief revision. If the goals are inconsistent, then this can be seen as a form of ampliative reasoning. We prove that determining if there is an arbitrary public announcement in this setting is not only decidable, but that it is simpler than the corresponding problem in the most simplified modal logics. Moreover, we argue that propositional announcements and beliefs are sufficient for modelling many practical problems, including simple robot controllers., Conference paper, Published.
Assessment of building retrofit options using hygrothermal analysis tool
Proceedings of 7th Symposium on Building Physics in the Nordic Countries: 13 June 2005, Reykjavik, Iceland. As the stock of buildings in our society ages, it is expected that there will be an increase in building envelope rehabilitation work. Such activities represent an ideal opportunity to modify the existing wall system to improve building envelope durability and energy efficiency. This could be done by addition of insulation and sealing air leakage paths. However, there is very little information available on how to assess the moisture and energy (i.e. thermal) performance of retrofitted building envelope assemblies and select the optimum retrofit options that will maximize the long-term moisture performance and the energy efficiency of the retrofitted building envelopes together. This paper presents the findings from a study that has used a two-dimensional hygrothermal simulation tool, hygIRC-2D, to assess moisture and energy performance of retrofitted masonry walls used in high-rise construction for both residential and commercial types of buildings at various Canadian locations. The results from the simulations indicate that, if heat, air and moisture transport properties of the materials and the airflow characteristics of the systems can be defined properly a hygrothermal simulation tool can be used to evaluate the moisture and thermal (i.e. energy) performance of various wall systems and associated retrofit options., Published. A version of this document is published in: 7th Symposium on Building Physics in the Nordic Countries, Reykjavik, Iceland, June 13-15, 2005, pp. 1139-1146.
Belief manipulation through propositional announcements
Proceedings of the Twenty-Sixth International Joint Conference on Artificial Intelligence (IJCAI-17) in Melbourne, Australia 19-25 August 2017. Public announcements cause each agent in a group to modify their beliefs to incorporate some new piece of information, while simultaneously being aware that all other agents are doing the same. Given a set of agents and a set of epistemic goals, it is natural to ask if there is a single announcement that will make each agent believe the corresponding goal. This problem is known to be undecidable in a general modal setting, where the presence of nested beliefs can lead to complex dynamics. In this paper, we consider not necessarily truthful public announcements in the setting of AGM belief revision. We prove that announcement finding in this setting is not only decidable, but that it is simpler than the corresponding problem in the most simplified modal logics. We then describe an implemented tool that uses announcement finding to control robot behaviour through belief manipulation., Conference paper, Published.
Belief modeling for maritime surveillance
Proceedings of 12th International Conference on Information Fusion, 2009, FUSION '09 in Seattle, WA, USA, 6-9 July 2009. In maritime surveillance, the volume of information to be processed is very large and there is a great deal of uncertainty about the data. There are many vessels at sea at every point in time, and the vast majority of them pose no threat to security. Sifting through all of the benign activity to find unusual activities is a difficult problem. The problem is made even more difficult by the fact that the available data about vessel activities is both incomplete and inconsistent. In order to manage this uncertainty, automated anomaly detection software can be very useful in the early detection of threats to security. This paper introduces a high-level architecture for an anomaly detection system based on a formal model of beliefs with respect to each entity in some domain of interest. In this framework, the system has beliefs about the intentions of each vessel in the maritime domain. If the vessel behaves in an unexpected manner, these intentions are revised and a human operations centre worker is notified. This approach is flexible, scalable, and easily manages inconsistent information. Moreover, the approach has the pragmatic advantage that it uses expert information to inform decision making, but the required information is easily obtained through simple ranking exercises., Conference paper, Published.
Belief revision and trust
Proceedings of the 15th International Workshop on Non-Monotonic Reasoning (NMR 2014), Vienna, Austria, 17–19 July 2014. Belief revision is the process in which an agent incorporates a new piece of information together with a pre-existing set of beliefs. When the new information comes in the form of a report from another agent, then it is clear that we must first determine whether or not that agent should be trusted. In this paper, we provide a formal approach to modeling trust as a pre-processing step before belief revision. We emphasize that trust is not simply a relation between agents; the trust that one agent has in another is often restricted to a particular domain of expertise. We demonstrate that this form of trust can be captured by associating a state-partition with each agent, then relativizing all reports to this state partition before performing belief revision. In this manner, we incorporate only the part of a report that falls under the perceived domain of expertise of the reporting agent. Unfortunately, state partitions based on expertise do not allow us to compare the relative strength of trust held with respect to different agents. To address this problem, we introduce pseudometrics over states to represent differing degrees of trust. This allows us to incorporate simultaneous reports from multiple agents in a way that ensures the most trusted reports will be believed., Conference paper, Published.
Belief revision on modal accessibility relations
Proceedings of the 6th International Conference on Agents and Artificial Intelligence in Angers, France, 2014. In order to model the changing beliefs of an agent, one must actually address two distinct issues. First, one must devise a model of static beliefs that accurately captures the appropriate notions of incompleteness and uncertainty. Second, one must define appropriate operations to model the way beliefs are modified in response to different events. Historically, the former is addressed through the use of modal logics and the latter is addressed through belief change operators. However, these two formal approaches are not particularly complementary; the normal representation of belief in a modal logic is not suitable for revision using standard belief change operators. In this paper, we introduce a new modal logic that uses the accessibility relation to encode epistemic entrenchment, and we demonstrate that this logic captures AGM revision. We consider the suitability of our new representation of belief, and we discuss potential advantages to be exploited in future work., Conference paper, Published.
Bluetooth for decoy systems
Proceedings of 2017 IEEE Conference on Communications and Network Security (CNS) in Las Vegas, NV, USA, USA, 9-11 Oct. 2017. We present an approach to tracking the behaviour of an attacker on a decoy system, where the decoy communicates with the real system only through low energy bluetooth. The result is a low-cost solution that does not interrupt the live system, while limiting potential damage. The attacker has no way to detect that they are being monitored, while their actions are being logged for further investigation. The system has been physically implemented using Raspberry PI and Arduino boards to replicate practical performance., Conference paper, Published.
Blurring boundaries: emergent technological practices of post-secondary students with mathematics learning disabilities
Not peer reviewed, Conference paper, Not yet published, conference in November 2019.
Building science integrated systems methodological framework
Proceedings from Architectural Engineering Conference 2013, April 3-5, 2013 at State College, Pennsylvania, United States. Building performance is governed by physical processes, which are dynamically coupled in time and space, and whose degrees of interactions are often difficult to measure and appreciate. As a result, suboptimal performance and failures often occur. The goal of high-performance buildings is to optimize major aspects such as energy efficiency, life-cycle costs, and lighting, which are tightly coupled by the underlying physical processes. The premise behind this research project is that building integration/optimization can only be achieved when grounded on a shared understanding and communication of the underlying physical principles governing building performance, which can then enable the transformation of these principles into meaningful performance metrics. This paper proposes a methodology for building systems integration through building science principles. At the core of the methodology, a vocabulary of building science concepts, principles, and metrics enables using existing knowledge to increase understanding and gain insights on the systems involved in a particular design (including degrees of coupling, redundancies, and behaviours), which in turn facilitates the creation of new knowledge that may be needed to integrate new systems and technologies. A set of generic building science rules implemented using systems theory will enable such knowledge creation while preserving systems integrity at all times. The goal of this research is not to create a knowledge-base to replace building science professionals but to leverage an explicit vocabulary to increase understanding, learning, and communication of building performance for improved building integration. Furthermore, it is envisioned that the knowledge-base will serve as a bridge between building simulation, decision analysis, and optimization. This paper presents the initial attempt to organize a wealth of building science knowledge into a structured vocabulary. The power of generality and usability of the methodology will be tested with a case study. The expected benefits of the approach are three-fold: 1) to promote a more systematic approach to optimize building systems, 2) to facilitate the integration of new systems and technologies in buildings, and 3) to improve the education and dissemination of building science knowledge for improved building integration., Peer reviewed, Conference proceeding, Published.

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