Research in authentication protocols has largely focused on developing and analyzing protocols that are secure against certain types of attacks. There is little and only scattered discussion on protocol efficiency. This paper presents results on the lower bounds on the numbers of messages and rounds required for network authentication. For each proven lower bound, an authentication protocol achieving the bound is also given, thus proving that the bound is a tight bound if the given optimal protocol is secure. 1 Introduction Authentication is by definition a process to verify one's claim of identity. Since authentication is usually a prelude to further communication and computation, an authentication protocol often arranges that the protocol participants, once their identities are verified, agree upon an encryption key--- a temporary key---for later use (e.g., within a user session). Thus an authentication protocol is sometimes also called a key distribution protocol. Current research...

Modern logic is often defined in terms of specific formal languages, rules, and calculi. Such architectural decisions about a field form a pervasive implicit definition which determines professional practice -- through the structure of textbooks, as well as the research agenda that determines 'interest', and hence acceptance and academic status. Such a practice may come to contain a lot of historical accident, or force of habit. Therefore, it seems worth thinking about the defining agenda of a field once in a while. In this brief essay, we explore alternative views of logic, locating the nature of the field in more abstract themes, concerns and attitudes. The new definition does not remove the need for the old agenda, but we advocate a shift in emphasis, toward greater generality and range of application. The outcome is a conception of logic as a broad methodological stance, looking for invariants in (information) structures and processes. to appear in A. Varzi, ed. "The European Revie...

We have a philosophy about incorporating technology into instruction that is grounded in the experience gained from our

This discussion note argues for embedding any formalization of semiformal notations in a methodology. I present a methodological framework for software specification based on systems engineering and show how the UML fits into this framework. Next, an essential modeling approach to formalizing the UML within this framework is argued. Finally, a transition system semantics for the UML is discussed, that fits this semantics approach. No formal details are given, but references are given to places where these can be found. 1 Formalism and Method Current research of several research groups is oriented to formalizing diagrammatic specification techniques [5, 9, 20, 37]. There is a close connection between the intended semantics of a notation for system specifications on the one hand and the intended method for system specification on the other. For example, if the method distinguishes a specification level from an implementation (programming language) level, as is done in Syntropy [6], then...

Abstract. In ill-defined domains, argumentation skills are essential in order to define problems and to present, justify, and evaluate solutions. In well-defined domains there exist accepted methods of characterizing student arguments as good or bad. This is not always possible in ill-defined domains, where competing arguments are often acceptable. In this paper, we use a set of statistical analysis methods to investigate whether, despite the lack of an “ideal solution,”, student-produced argument diagrams can be diagnostic in that they can be used to reliably classify students into novices and experts or high and low aptitude. Our analysis, based on data collected during three studies with the LARGO ITS, suggests that indeed, argument graphs created by different student populations differ considerably, particularly with respect to the completeness and “connectedness ” of graphs, and can thus potentially be used to adapt the system to a particular student’s needs.

Z3 [3] is a state-of-the-art Satisfiability Modulo Theories (SMT) solver freely available from Microsoft Research. It solves the decision problem for quantifier-free formulas with respect to combinations of theories, such as arithmetic, bit-vectors, arrays, and uninterpreted functions. Z3 is used in various software analysis and test-case generation projects at Microsoft Research and elsewhere. The requirements from the user-base range from establishing validity, dually unsatisfiability, of firstorder formulas; to identify invalid, dually satisfiable, formulas. In both cases, there is often a need for more than just a yes/no answer from the prover. A model can exhibit why an invalid formula is not provable, and a proof-object can certify the validity of a formula. This paper describes the proof-producing internals of Z3. We also briefly introduce the model-producing facilities. We emphasize two features that can be of general interest: (1) we introduce a notion of implicit quotation to avoid introducing auxiliary variables, it simplifies the creation of proof objects considerably; (2) we produce natural deduction style proofs to facilitate modular proof re-construction.

this paper would be "G odel, Lucas, Penrose, Turing, Feferman, Dummett, mechanism, optimism, reflection, and indefinite extensibility". Adding "God and the Devil" would probably be redundant. Despite the breath-taking, whirlwind tour, I have the modest aim of forging connections between di#erent parts of this literature and clearing up some confusions, together with the less modest aim of not introducing any more confusions.

Christopher Koch [34] accurately captures a great scientific distaste for philosophizing: “Whether we scientists are inspired, bored, or infuriated by philosophy, all our theorizing and experimentation depends on particular philosophical background assumptions. This hidden influence is an acute embarrassment to many researchers, and it is therefore not often acknowledged. ” (Christopher Koch, 2004) That acknowledged, I am of the opinion that mathematical philosophy matters more now than it has in nearly a century. The power of modern computers matched with that of modern mathematical software and the sophistication of current mathematics is changing the way we do mathematics. In my view it is now both necessary and possible to admit quasi-empirical inductive methods fully into mathematical argument. In doing so carefully we will enrich mathematics and yet preserve the mathematical literature’s deserved reputation for reliability—even as the methods and criteria change. What do I mean by reliability? Well, research mathematicians still consult Euler or Riemann to be informed, anatomists only consult Harvey 3 for historical reasons. Mathematicians happily quote old papers as core steps of arguments, physical scientists expect to have to confirm results with another experiment. 1 Mathematical Knowledge as I View It Somewhat unusually, I can exactly place the day at registration that I became a mathematician and I recall the reason why. I was about to deposit my punch cards in the ‘honours history bin’. I remember thinking “If I do study history, in ten years I shall have forgotten how to use the calculus properly. If I take mathematics, I shall still be able to read competently about the War of 1812 or the Papal schism. ” (Jonathan Borwein, 1968) The inescapable reality of objective mathematical knowledge is still with me. Nonetheless, my view then of the edifice I was entering is not that close to my view of the one I inhabit forty years later. 1 The companion web site is at www.experimentalmath.info

Abstract. The vision of a computerised assistant to mathematicians has existed since the inception of theorem proving systems. The Alcor system has been designed to investigate and explore how a mathematician might interact with such an assistant by providing an interface to Mizar and the Mizar Mathematical Library. Our current research focuses on the integration of searching and authoring while proving. In this paper we use a scenario to elaborate the nature of the interaction. We abstract from this two distinct types of searching and describe how the Alcor interface implements these with keyword and LSI-based search. Though Alcor is still in its early stages of development, there are clear implications for the general problem of integrating searching and authoring, as well as technical issues with Mizar.

We argue that negotiation over the meaning of terms in a statement is part of human discussion and that it can lead to richer theories. We describe our preliminary model of semantic negotiation and discuss theoretical examples which we hope to implement. Finally we consider how semantic negotiation ts into existing work on argumentation.