A mechanized proof of loop freedom of the (untimed) AODV routing protocol

The Ad hoc On-demand Distance Vector (AODV) routing protocol allows the nodes in a Mobile Ad hoc Network (MANET) or a Wireless Mesh Network (WMN) to know where to forward data packets. Such a protocol is 'loop free' if it never leads to routing decisions that forward packets in circles. This paper describes the mechanization of an existing pen-and-paper proof of loop freedom of AODV in the interactive theorem prover Isabelle/HOL. The mechanization relies on a novel compositional approach for lifting invariants to networks of nodes. We exploit the mechanization to analyse several improvements of AODV and show that Isabelle/HOL can re-establish most proof obligations automatically and identify exactly the steps that are no longer valid.Comment: The Isabelle/HOL source files, and a full proof document, are available in the Archive of Formal Proofs, at http://afp.sourceforge.net/entries/AODV.shtm

Mechanizing a Process Algebra for Network Protocols

This paper presents the mechanization of a process algebra for Mobile Ad hoc Networks and Wireless Mesh Networks, and the development of a compositional framework for proving invariant properties. Mechanizing the core process algebra in Isabelle/HOL is relatively standard, but its layered structure necessitates special treatment. The control states of reactive processes, such as nodes in a network, are modelled by terms of the process algebra. We propose a technique based on these terms to streamline proofs of inductive invariance. This is not sufficient, however, to state and prove invariants that relate states across multiple processes (entire networks). To this end, we propose a novel compositional technique for lifting global invariants stated at the level of individual nodes to networks of nodes.Comment: This paper is an extended version of arXiv:1407.3519. The Isabelle/HOL source files, and a full proof document, are available in the Archive of Formal Proofs, at http://afp.sourceforge.net/entries/AWN.shtm

Formalising the Optimised Link State Routing Protocol

Routing protocol specifications are traditionally written in plain English. Often this yields ambiguities, inaccuracies or even contradictions. Formal methods techniques, such as process algebras, avoid these problems, thus leading to more precise and verifiable descriptions of protocols. In this paper we use the timed process algebra T-AWN for modelling the Optimised Link State Routing protocol (OLSR) version 2.Comment: In Proceedings MARS 2020, arXiv:2004.1240

Programming Languages and Systems

This open access book constitutes the proceedings of the 28th European Symposium on Programming, ESOP 2019, which took place in Prague, Czech Republic, in April 2019, held as Part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2019

Active Materials

What is an active material? This book aims to redefine perceptions of the materials that respond to their environment. Through the theory of the structure and functionality of materials found in nature a scientific approach to active materials is first identified. Further interviews with experts from the natural sciences and humanities then seeks to question and redefine this view of materials to create a new definition of active materials

Active Materials

What is an active material? This book aims to redefine perceptions of the materials that respond to their environment. Through the theory of the structure and functionality of materials found in nature a scientific approach to active materials is first identified. Further interviews with experts from the natural sciences and humanities then seeks to question and redefine this view of materials to create a new definition of active materials

Endogenous development: a model for the process of man-environment transaction

Iran is currently subject to a number of adverse factors affecting good development in the built environment: population explosion, oil- dependent economy, finite resources, war and natural disasters, etc. The object of the study is to research a development model appropriate to the Country's needs for a proactive system of building environment. This model is not specific to Iran and, as the case studies and the discourse of the thesis indicate, is universal. However, the author suggests that the validity of development approaches will not be determined as a result of theoretical and ideological debate but in the realm of practice. Therefore, he has explored diverse ways in which professionals in the built environment can provide an analytical survey of the problems that beset them. An attempt has been made to bring these various elements into perspective and offer a model of 'endogenous development'.The process for achieving a viable, exciting and humane built environment is very complex and calls for contributions from many individuals and small multi -disciplinary groups. Beside professionals contributions (which is accomplished by deduction inference), there is a need for people's participation in design process (which is accomplished either by deduction or by abduction inferences). This participatory approach can also help shifting the process of design towards a wider domain that of the 'production process' (which is accomplished by abduction and induction inferences). Production process is the first paradigm of the model of endogenous development and is a manifestation of a feedback mechanism and acts as an open - ended living system. The second is 'supply- demand' paradigm which shows the relationships between the components of a system or between different systems in surface- structuresThis model is directed at society's development, not just its economic growth, but it does not preclude the possibility of such growth. The reduction of the problems' effect in an endogenous development is viewed more as a way of improving the quality of life than of increasing the standard of living. Nowadays, people are passive recipients in the consumer society and are totally dependent on others for their survival. This style of living is assumed to project an image of economic development and higher productivity, but there is a confrontation of preadjusted commodities which are the products of others. That is because the process of production is not natural (i.e. a closed loop cyclic process via feedback control). It is artificial (i.e. an open -loop linear process via a feed -forward control) which may not help satisfying the user's needs and wants entirely. In the built environment, the great majority have no say in the planning and design of their homes or places of work.Accordingly, endogenous development offers a framework within which the necessity of employing the people's creative power in building their environment is explained. It is based on the assumption that each individual and society's knowledge and experiences play a central and mediating role between professionals' perceptions of the environment and a series of preferences judgements or choices they might make towards and within that environment. Indigenous knowledge and cultural attributes of traditional societies and the organizational capabilities of traditional polities are essential in qualification of the development plans, which are also evaluated and assessed by this proposed framework

2007-2008 Course Catalog

2007-2008 Course Catalo

2005 BRAC Commission

Contains notes and research (Socio-economic issues raised by staff/Commissioners) Various States by Bob Cook of the INTERAGENCY Team