Abdur Rakib

Logic for coalitions with bounded resources1

Recent work on Alternating-Time Temporal Logic and Coalition Logic has allowed the expression of many interesting properties of coalitions and strategies. However there is no natural way of expressing resource requirements in these logics. This paper presents a Resource-Bounded Coalition Logic (RBCL) which has explicit representation of resource bounds in the language, and gives a complete and sound axiomatisation of RBCL.

Verifying time, memory and communication bounds in systems of reasoning agents

We present a framework for verifying systems composed of heterogeneous reasoning agents, in which each agent may have differing knowledge and inferential capabilities, and where the resources each agent is prepared to commit to a goal (time, memory and communication bandwidth) are bounded. The framework allows us to investigate, for example, whether a goal can be achieved if a particular agent, perhaps possessing key information or inferential capabilities, is unable (or unwilling) to contribute more than a given portion of its available computational resources or bandwidth to the problem. We present a novel temporal epistemic logic, BMCL-CTL, which allows us to describe a set of reasoning agents with bounds on time, memory and the number of messages they can exchange. The bounds on memory and communication are expressed as axioms in the logic. As an example, we show how to axiomatise a system of agents which reason using resolution and prove that the resulting logic is sound and complete. We then show how to encode a simple system of reasoning agents specified in BMCL-CTL in the description language of the Mocha model checker (Alur et al., Proceedings of the tenth international conference on computer-aided verification (CAV), 1998), and verify that the agents can achieve a goal only if they are prepared to commit certain time, memory and communication resources.

Verifying Time and Communication Costs of Rule-Based Reasoners

We present a framework for the automated verification of time and communication requirements in systems of distributed rule-based reasoning agents which allows us to determine how many rule-firing cycles are required to solve the problem, how many messages must be exchanged, and the trade-offs between the time and communication resources. We extend CTL* with belief and communication modalities to express bounds on the number of messages the agents can exchange. The resulting logic,

Component-Wise Instruction-Cache Behavior Prediction

\mathcal{L}_{CRB}

Expressing properties of coalitional ability under resource bounds

, can be used to express both bounds on time and on communication. We provide an axiomatisation of the logic and prove that it is sound and complete. Using a synthetic but realistic example system of rule-based reasoning agents which allows the size of the problem and the distribution of knowledge among the reasoners to be varied, we show the Mocha model checker [1] can be used to encode and verify properties of systems of distributed rule-based agents. We describe the encoding and report results of model checking experiments which show that even simple systems have rich patterns of trade-offs between time and communication bounds.

A Formal Approach to Modelling and Verifying Resource-Bounded Context-Aware Agents

The precise determination of worst-case execution times (WCETs) for programs is mostly being performed on fully linked executables, since all needed information is available and all machine parameters influencing cache performance are available to the analysis. This paper describes how to perform a component-wise prediction of the instruction cache behavior guaranteeing conservative results compared to an analysis of a fully linked executable. This proves the correctness of the method based on a previous proof of correctness of the analysis of fully linked executables. The analysis is described for a general A-way set associative cache. The only assumption is that the replacement strategy is LRU.

Automated verification of resource requirements in multi-agent systems using abstraction

We introduce Coalition Logic for Resource Games (CLRG) which extends Coalition Logic by allowing explicit reasoning about resource endowments of coalitions of agents and resource bounds on strategies. We show how to express interesting properties of coalitional ability under resource bounds in this logic, including properties of Coalitional Resource Games introduced by Wooldridge and Dunne in [1]. We also give an efficient model-checking algorithm for CLRG which makes it possible to verify the properties automatically.

Reasoning about Other Agents' Beliefs under Bounded Resources

There has been a move of context-aware systems into safety-critical domains including healthcare, emergency scenarios, and disaster recovery. These systems are often distributed and deployed on resource-bounded devices. Therefore, developing formal techniques for modelling and designing context-aware systems, verifying requirements and ensuring functional correctness are major challenges. We present a framework for the formal representation and verification of resource-bounded context-aware systems. We give ontological representation of contexts, translate ontologies to a set of Horn clause rules, based on these rules we build multi-agent context-aware systems and encode them into Maude specification, we then verify interesting properties of such systems using the Maude LTL model checker.

A Framework for Implementing Formally Verified Resource-Bounded Smart Space Systems

We describe a framework for the automated verification of multi-agent systems which do distributed problem solving, e.g., query answering. Each reasoner uses facts, messages and Horn clause rules to derive new information. We show how to verify correctness of distributed problem solving under resource constraints, such as the time required to answer queries and the number of messages exchanged by the agents. The framework allows the use of abstract specifications consisting of Linear Time Temporal Logic (LTL) formulas to specify some of the agents in the system. We illustrate the use of the framework on a simple example.

Resource-bounded alternating-time temporal logic

There exists a considerable body of work on epistemic logics for bounded reasoners where the bound can be time, memory, or the amount of information the reasoners can exchange. In much of this work the epistemic logic is used as a meta-logic to reason about beliefs of the bounded reasoners from an external perspective. In this paper, we present a formal model of a system of bounded reasoners which reason about each others beliefs, and propose a sound and complete logic in which such reasoning can be expressed. Our formalisation highlights a problem of incorrect belief ascription in resource-bounded reasoning about beliefs, and we propose a possible solution to this problem, namely adding reasoning strategies to the logic.