Optimal Union-Find in Constraint Handling Rules

Constraint Handling Rules (CHR) is a committed-choice rule-based language that was originally intended for writing constraint solvers. In this paper we show that it is also possible to write the classic union-find algorithm and variants in CHR. The programs neither compromise in declarativeness nor efficiency. We study the time complexity of our programs: they match the almost-linear complexity of the best known imperative implementations. This fact is illustrated with experimental results.Comment: 12 pages, 3 figures, to appear in Theory and Practice of Logic Programming (TPLP

Chippe : a system for constraint driven behavioral synthesis

This report describes the Chippe system, gives some background previous work and describes several sample design runs of the system. Also presented are the sources of the design tradeoffs used by Chippe, and overview of the internal design model, and experiences using the system

Description and Optimization of Abstract Machines in a Dialect of Prolog

In order to achieve competitive performance, abstract machines for Prolog and related languages end up being large and intricate, and incorporate sophisticated optimizations, both at the design and at the implementation levels. At the same time, efficiency considerations make it necessary to use low-level languages in their implementation. This makes them laborious to code, optimize, and, especially, maintain and extend. Writing the abstract machine (and ancillary code) in a higher-level language can help tame this inherent complexity. We show how the semantics of most basic components of an efficient virtual machine for Prolog can be described using (a variant of) Prolog. These descriptions are then compiled to C and assembled to build a complete bytecode emulator. Thanks to the high level of the language used and its closeness to Prolog, the abstract machine description can be manipulated using standard Prolog compilation and optimization techniques with relative ease. We also show how, by applying program transformations selectively, we obtain abstract machine implementations whose performance can match and even exceed that of state-of-the-art, highly-tuned, hand-crafted emulators.Comment: 56 pages, 46 figures, 5 tables, To appear in Theory and Practice of Logic Programming (TPLP

Implementation of Event-Based Dynamic Authentication on MQTT Protocol

This paper proposes an authentication mechanism on the MQ Telemetry Transport (MQTT) protocol. The exchange of data in the IoT system became an important activity. The MQTT protocol is a fast and lightweight communication protocol for IoT. One of the problems with the MQTT protocol is that there is no security mechanism in the initial setup. One security attack may occur during the client registration phase. The client registration phase has a vulnerability to accept false clients due to the absence of an authentication mechanism. An authentication mechanism has been previously made using Transport Layer Security (TLS). However, the TLS mechanism consumes more than 100 KB of data memory and is not suitable for devices that have limitations. Therefore, a suitable authentication mechanism for constraint devices is required. This paper proposes a protocol for authentication mechanisms using dynamic and event-based authentication for the MQTT protocol. The eventbased is used to reduce the computing burden of constraint devices. Dynamic usage is intended to provide different authentication properties for each session so that it can improve authentication security. As results, the applied of the event-based dynamic authentication protocol was successful in the constraint devices of  microcontrollers and broker. The microcontroller, as a client, is able to process the proposed protocol. The client uses 52% of the memory for the proposed protocol and only consumes 2% higher than the protocol without security. The broker can find authentic clients and constraint devices capable of computing to carry out mutual authentication processes to clients. The broker uses a maximum of 4.3 MB of real memory and a maximum CPU usage of 3.7%