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String processing
Published in Rafael A. Irizarry, Introduction to Data Science, 2019
4. Extract the ninth page of the PDF file from the object txt, then use the str_split from the stringr package so that you have each line in a different entry. Call this string vector s. Then look at the result and choose the one that best describes what you see. It is an empty string.I can see the figure shown in page 1.It is a tidy table.I can see the table! But there is a bunch of other stuff we need to get rid of.
Modeling and state estimation for supervisory control of networked timed discrete-event systems and their application in supervisor synthesis
Published in International Journal of Control, 2023
Yunfeng Hou, Yunfeng Ji, Gang Wang, Ching-Yen Weng, Qingdu Li
We model a TDES using a deterministic finite-state timed automaton with a special event tick representing the elapse of one unit of time. The timed automaton is introduced in Brandin and Wonham (1994) as: , where is the finite set of events; is the transition function; is the active event function; is the initial state; is the set of marked states. is the Kleene Closure of , i.e. the set of all strings over events in . δ is extended to the domain in the usual way (Cassandras & Lafortune, 2007). The languages generated and marked by G are denoted by and , respectively. ε is the empty string. The accessible part of G, denoted by , is the automaton obtained by removing all the states that are not reachable from the initial state and all the transitions that are connected to these states.
Current-state opacity and initial-state opacity of modular discrete event systems
Published in International Journal of Control, 2022
Jingkai Yang, Weilin Deng, Daowen Qiu
A DES is modelled as a finite state automaton , where Q the finite state set, Σ the finite event set, the initial state set and is the (partial) transition function. The transition function δ can be extended to as usual, where denotes the set of strings with finite length over Σ. The language generated by G is defined by , where ‘!’ means ‘is defined’, and the language generated by G originating from state q is defined by . For any string , denotes the length of string s. Let ε be the empty string, that is, .
Intelligent evaluation of test suites for developing efficient and reliable software
Published in International Journal of Parallel, Emergent and Distributed Systems, 2021
Masoud Mohammadian, Zafer Javed
We then devise equivalence classes for these levels. We denote the length of the string and the pattern by SLENGTH and PLENGTH, respectively. In L1, we devise the equivalence classes based on the length of the string. The strings with four or more characters are put into the same category (equivalence class). Therefore, the L1 equivalence classes are the following: Empty string (SLENGTH = 0).Strings that contain one character (SLENGTH = 1).Strings that contain two characters (SLENGTH = 2).Strings that contain three characters (SLENGTH = 3).Strings that contain four or more characters (SLENGTH ≥ 4).