When packet loss rate exceeds a given threshold, received audio and video become unintelligible. A congested router transmitting multimedia packets, while inflicting a packet loss rate beyond a given threshold, effectively transmits useless packets. Useless packet transmission wastes router bandwidth when it is needed most. We propose an algorithm to avoid transmission of useless multimedia pac...

In this paper, we study program transformations called uselesscode elimination and program slicing in the context of the π-calculus. The aim of useless-code elimination and program slicing is to simplify a program by eliminating useless or unimportant part of the program. We define formal correctness criteria for those transformations, present a type-based transformation method, and prove its c...

PERSPECTIVES C an you reliably send information down a telegraph wire that doesn't always transmit signals correctly? Claude Shannon put classical information theory on a firm footing when he showed that you can correct for transmission errors as long as there is some tiny correlation between what gets sent and what is received. What's more, Shannon quantified how much information could be reli...

We investigate the fundamental constraint on amplifying asymmetry in quantum states with correlating catalysts. Here a catalyst is finite-dimensional auxiliary, which exactly preserves its reduced state while allowed to become correlated system. Interestingly, we prove that under translationally invariant operations, uncorrelating catalysts pure are useless any transformation, catalyst, one can...

Planning for partially observable, nondeterministic domains is a very significant and computationally hard problem. Often, reasonable assumptions can be drawn over expected/nominal dynamics of the domain; using them to constrain the search may lead to dramatically improve the efficiency in plan generation. In turn, the execution of assumption-based plans must be monitored to prevent runtime fai...

The computation of the answer sets in Answer Set Programming (ASP) ASP systems is performed on simple ground (i.e., variable free) programs, first computed by a pre-processing phase, called instantiation. This phase may be computationally expensive, and in fact it has been recognized to be a key issue for solving real-world problems by using Answer Set Programming. Given a program P , a good in...

Useless paths are a chronic problem for marker-passing techniques. We use a prob­ abilistic analysis to justify a method for quickly identifying and rejecting useless paths. Using the same analysis, we identify key conditions and assumptions necessary for marker-passing to perform well.

Fault Tolerance Techniques enable systems to perform tasks in the presence of faults. A checkpoint is a local state of a process saved on stable storage. In a distributed system, since the processes in the system do not share memory, a global state of the system is defined as a set of local states, one from each process. In case of a fault in distributed systems, checkpointing enables the execu...