Ing. Tomáš Pecka

Stať ve sborníku

10.1109/ECOC52684.2021.9605935

Katedra teoretické informatiky

An interactive demo presents live, real-time optical performance monitoring of the optical spectrum from an Open Optical Line System. Built with open source software, open hardware, and using standard YANG tooling, we achieve a sub-GHz resolution and a sub-second refresh rate over the C-band.

Článek

10.1364/JOCN.425167

Katedra teoretické informatiky

We present an implementation of streaming telemetry of optical metrics within open hardware reconfigurable add/drop multiplexers (ROADMs). Our key achievements are sub-second updates of high-resolution spectrum scans, and we demonstrate a sustained telemetry stream of the full C-band with a sub-GHz resolution. The telemetry streaming is implemented over a standard, Internet Engineering Task Force (IETF)-defined protocol (YANG Push) in collaboration with an open-source YANG software stack and device-specific code. As the telemetry collector, we used a common time series database (TSDB) along with a visualization dashboard. We also extended the Open Network Operating System (ONOS) software-defined network (SDN) controller to act as a telemetry receiver.

Stať ve sborníku

Katedra teoretické informatiky

Regular tree languages can be accepted and described by finite tree automata and regular tree expressions, respectively. We describe a new algorithm that converts a finite tree automaton to an equivalent regular tree expression. Our algorithm is analogous to the well-known state elimination method of the conversion of a string finite automaton to an equivalent string regular expression. We define a generalised finite tree automaton, the transitions of which read the sets of trees described by regular tree expressions. Our algorithm eliminates states of the generalised finite tree automaton, which is analogous to the elimination of states in converting the string finite automaton.

Stať ve sborníku

Katedra teoretické informatiky

We define a tree pattern border array as a property of linearised trees analogous to border arrays from the string domain. We use it to define a new forward tree pattern matching algorithm for ordered trees, which finds all occurrences of a single given linearised tree pattern in a linearised input tree. As with the classical Morris-Pratt algorithm, the tree pattern border array is used to determine shift lengths in the matching phase of the tree pattern matching algorithm. We compare the new algorithm with the best performing previously existing algorithms based on backward linearised tree pattern matching algorithms, (non-)linearised tree pattern matching algorithms using finite tree automata or stringpath matchers. We show that the presented algorithm outperforms these for single tree pattern matching.

Stať ve sborníku

10.4230/OASIcs.SLATE.2018.6

Katedra teoretické informatiky

Regular tree expressions are a formalism for describing regular tree languages, which can be accepted by a finite tree automaton as a standard model of computation. It was proved that the class of regular tree languages is a proper subclass of tree languages those linear notations can be accepted by deterministic string pushdown automata. In this paper, we present a new algorithm for transforming regular tree expressions to equivalent real-time height-deterministic pushdown automata that accept the trees in their postfix notation.