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Compiler Construction WS 10/11 Solution -Exam 01.02.2011

Summary: 2
Compiler Construction WS 10/11
Solution - Exam 01.02.2011
aaPriv.-Doz. Dr. T. Noll, C. Jansen
Aufgabe 1 (Lexical Analysis): (3+7+4+2 = 16 Points)
Assume you would like to automatically tag your audio files with information extracted from their filenames. You
decide to categorise the extracted information into three classes:
· TY PE {AB, MU}, tells whether your file contains an audiobook (AB) or a piece of music (MU)
· DESC, an arbitrary non-empty string of letters and numbers, which contains the description of the file, i.e.
title, artist etc.
· EXT {MP3, AAC} indicating the audio format of the file
Example: The file "MP3-Compiler-AB.MP3" should be tagged with TY PE = AB, DESC = Compiler, EXT =
a) Construct regular expressions T Y P E, DESC, EXT and give corresponding DFAs AT Y P E, ADESC, AEXT
such that L(AT Y P E) = T Y P E , L(ADESC) = DESC , L(AEXT ) = EXT .
b) Construct the backtracking automaton A accepting
1 := T Y P E, 2 := EXT , 3 := DESC
and additionally
4 := SEP = -, 5 := DOT = .
c) Compute the run of A for the input word w = MU - MUH.MP3.


Source: Ábrahám, Erika - Fachgruppe Informatik, Rheinisch Westfälische Technische Hochschule Aachen (RWTH)


Collections: Computer Technologies and Information Sciences