Safe Compositional Specification of Networking Systems: A Compositional Analysis Approach

We present a type inference algorithm, in the style of compositional analysis, for the language TRAFFIC—a specification language for flow composition applications proposed in [2]—and prove that this algorithm is correct: the typings it infers are principal typings, and the typings agree with syntax-directed type checking on closed flow specifications. This algorithm is capable of verifying partial flow specifications, which is a significant improvement over syntax-directed type checking algorithm presented in [3]. We also show that this algorithm runs efficiently, i.e., in low-degree polynomial time.National Science Foundation (ITR ANI-0205294, ANI-0095988, ANI-9986397, EIA-0202067

Does liquidity in the FX market depend on volatility?

We re-examine the relationship between exchange rates and order flow as proposed by Evans and Lyons (2002). Compared to their linear specification, we find that the response of exchange rates to order flow may depend on market historical volatility. If market historical volatility is high, a given order seems to have a lower price impact than in calmer periods. Overall, our simple threshold mechanism has the power to produce higher correlation coefficients.exchange rate dynamics

A CASE tool supports the software life cycle of participator dependent multimedia presentations

[[abstract]]This paper presents a CASE tool for the specification, design, implementation, testing and maintenance of multimedia presentations. The proposed system is based on a Petri net machine to control event-based resource synchronization. Data flow diagrams and control flow diagrams are used as the specification of a multimedia presentation. The system then allows the specification to be stepwise refined toward the final multimedia presentation[[conferencetype]]國際[[conferencedate]]19980628~19980701[[booktype]]紙

Elasticity of trade flow to trade barriers: A comparison among emerging estimation techniques

The objective of this study has been to analyze the sensitivity of trade flow to trade barriers from gravity equations, using different econometric techniques recently highlighted in the literature. Specifically, we compare a benchmark OLS fixed effects specification a la Feenstra (2002), with three emerging estimation methods: the standard Heckman correction for selection bias, to account for zero trade flow; its extension, recently proposed by Helpman et al. (2008), to control for firm heterogeneity; and, finally, the Poisson pseudo-maximum-likelihood (PPML) technique to correct for the presence of heteroskedasticity, first proposed by Santos Silva and Tenreyro (2006). Our gravity model includes trade among 211 exporter and 104 importer countries, in 18 food industry sectors.Gravity model, Trade Elasticity, Food trade, International Relations/Trade,

Generating Predicate Callback Summaries for the Android Framework

One of the challenges of analyzing, testing and debugging Android apps is that the potential execution orders of callbacks are missing from the apps' source code. However, bugs, vulnerabilities and refactoring transformations have been found to be related to callback sequences. Existing work on control flow analysis of Android apps have mainly focused on analyzing GUI events. GUI events, although being a key part of determining control flow of Android apps, do not offer a complete picture. Our observation is that orthogonal to GUI events, the Android API calls also play an important role in determining the order of callbacks. In the past, such control flow information has been modeled manually. This paper presents a complementary solution of constructing program paths for Android apps. We proposed a specification technique, called Predicate Callback Summary (PCS), that represents the callback control flow information (including callback sequences as well as the conditions under which the callbacks are invoked) in Android API methods and developed static analysis techniques to automatically compute and apply such summaries to construct apps' callback sequences. Our experiments show that by applying PCSs, we are able to construct Android apps' control flow graphs, including inter-callback relations, and also to detect infeasible paths involving multiple callbacks. Such control flow information can help program analysis and testing tools to report more precise results. Our detailed experimental data is available at: http://goo.gl/NBPrKsComment: 11 page

A Data-Flow Language for Specifying Business Data Processing Applications

A high level specification language called Business Data-Flow Language (BDFL) based on the data-flow model of computation is described in this paper. A translator to convert BDFL Specifications into COBOL programs has been implemented. A novel feature of the proposed translation system is the use of Data Base Menagement Systems (DBMS) in conjunction with COBOL. This relieves the user of the need to design data structures for the intended Data Processing application

Dependencies and Separation of Duty Constraints in GTRBAC

A Generalized Temporal Role Based Access Control (GTRBAC) model that captures an exhaustive set of temporal constraint needs for access control has recently been proposed. GTRBAC’s language constructs allow one to specify various temporal constraints on role, user-role assignments and role-permission assignments. In this paper, we identify various time-constrained cardinality, control flow dependency and separation of duty constraints (SoDs). Such constraints allow specification of dynamically changing access control requirements that are typical in today’s large systems. In addition to allowing specification of time, the constraints introduced here also allow expressing access control policies at a finer granularity. The inclusion of control flow dependency constraints allows defining much stricter dependency requirements that are typical in workflow types of applications