25
|
1 |
\documentclass[dvipsnames,14pt,t]{beamer}
|
|
2 |
\usepackage{beamerthemeplainculight}
|
|
3 |
\usepackage[T1]{fontenc}
|
|
4 |
\usepackage[latin1]{inputenc}
|
|
5 |
\usepackage{mathpartir}
|
|
6 |
\usepackage[absolute,overlay]{textpos}
|
|
7 |
\usepackage{ifthen}
|
|
8 |
\usepackage{tikz}
|
|
9 |
\usepackage{pgf}
|
|
10 |
\usepackage{calc}
|
|
11 |
\usepackage{ulem}
|
|
12 |
\usepackage{courier}
|
|
13 |
\usepackage{listings}
|
|
14 |
\renewcommand{\uline}[1]{#1}
|
|
15 |
\usetikzlibrary{arrows}
|
|
16 |
\usetikzlibrary{automata}
|
|
17 |
\usetikzlibrary{shapes}
|
|
18 |
\usetikzlibrary{shadows}
|
|
19 |
\usetikzlibrary{positioning}
|
|
20 |
\usetikzlibrary{calc}
|
|
21 |
\usepackage{graphicx}
|
|
22 |
|
|
23 |
\definecolor{javared}{rgb}{0.6,0,0} % for strings
|
|
24 |
\definecolor{javagreen}{rgb}{0.25,0.5,0.35} % comments
|
|
25 |
\definecolor{javapurple}{rgb}{0.5,0,0.35} % keywords
|
|
26 |
\definecolor{javadocblue}{rgb}{0.25,0.35,0.75} % javadoc
|
|
27 |
|
|
28 |
\lstset{language=Java,
|
|
29 |
basicstyle=\ttfamily,
|
|
30 |
keywordstyle=\color{javapurple}\bfseries,
|
|
31 |
stringstyle=\color{javagreen},
|
|
32 |
commentstyle=\color{javagreen},
|
|
33 |
morecomment=[s][\color{javadocblue}]{/**}{*/},
|
|
34 |
numbers=left,
|
|
35 |
numberstyle=\tiny\color{black},
|
|
36 |
stepnumber=1,
|
|
37 |
numbersep=10pt,
|
|
38 |
tabsize=2,
|
|
39 |
showspaces=false,
|
|
40 |
showstringspaces=false}
|
|
41 |
|
|
42 |
\lstdefinelanguage{scala}{
|
|
43 |
morekeywords={abstract,case,catch,class,def,%
|
|
44 |
do,else,extends,false,final,finally,%
|
|
45 |
for,if,implicit,import,match,mixin,%
|
|
46 |
new,null,object,override,package,%
|
|
47 |
private,protected,requires,return,sealed,%
|
|
48 |
super,this,throw,trait,true,try,%
|
|
49 |
type,val,var,while,with,yield},
|
|
50 |
otherkeywords={=>,<-,<\%,<:,>:,\#,@},
|
|
51 |
sensitive=true,
|
|
52 |
morecomment=[l]{//},
|
|
53 |
morecomment=[n]{/*}{*/},
|
|
54 |
morestring=[b]",
|
|
55 |
morestring=[b]',
|
|
56 |
morestring=[b]"""
|
|
57 |
}
|
|
58 |
|
|
59 |
\lstset{language=Scala,
|
|
60 |
basicstyle=\ttfamily,
|
|
61 |
keywordstyle=\color{javapurple}\bfseries,
|
|
62 |
stringstyle=\color{javagreen},
|
|
63 |
commentstyle=\color{javagreen},
|
|
64 |
morecomment=[s][\color{javadocblue}]{/**}{*/},
|
|
65 |
numbers=left,
|
|
66 |
numberstyle=\tiny\color{black},
|
|
67 |
stepnumber=1,
|
|
68 |
numbersep=10pt,
|
|
69 |
tabsize=2,
|
|
70 |
showspaces=false,
|
|
71 |
showstringspaces=false}
|
|
72 |
|
|
73 |
% beamer stuff
|
|
74 |
\renewcommand{\slidecaption}{AFL 03, King's College London, 10.~October 2012}
|
|
75 |
\newcommand{\bl}[1]{\textcolor{blue}{#1}}
|
|
76 |
\newcommand{\dn}{\stackrel{\mbox{\scriptsize def}}{=}}% for definitions
|
|
77 |
|
|
78 |
\begin{document}
|
|
79 |
|
|
80 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
81 |
\mode<presentation>{
|
|
82 |
\begin{frame}<1>[t]
|
|
83 |
\frametitle{%
|
|
84 |
\begin{tabular}{@ {}c@ {}}
|
|
85 |
\\[-3mm]
|
|
86 |
\LARGE Automata and \\[-2mm]
|
|
87 |
\LARGE Formal Languages (3)\\[3mm]
|
|
88 |
\end{tabular}}
|
|
89 |
|
|
90 |
%\begin{center}
|
|
91 |
%\includegraphics[scale=0.3]{pics/ante1.jpg}\hspace{5mm}
|
|
92 |
%\includegraphics[scale=0.31]{pics/ante2.jpg}\\
|
|
93 |
%\footnotesize\textcolor{gray}{Antikythera automaton, 100 BC (Archimedes?)}
|
|
94 |
%\end{center}
|
|
95 |
|
|
96 |
\normalsize
|
|
97 |
\begin{center}
|
|
98 |
\begin{tabular}{ll}
|
|
99 |
Email: & christian.urban at kcl.ac.uk\\
|
|
100 |
Of$\!$fice: & S1.27 (1st floor Strand Building)\\
|
|
101 |
Slides: & KEATS (also home work is there)\\
|
|
102 |
& \alert{\bf (I have put a temporary link in there.)}\\
|
|
103 |
\end{tabular}
|
|
104 |
\end{center}
|
|
105 |
|
|
106 |
|
|
107 |
\end{frame}}
|
|
108 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
109 |
|
|
110 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
111 |
\mode<presentation>{
|
|
112 |
\begin{frame}[c]
|
|
113 |
\frametitle{\begin{tabular}{c}Last Week\end{tabular}}
|
|
114 |
|
|
115 |
Last week I showed you
|
|
116 |
|
|
117 |
\begin{itemize}
|
|
118 |
\item one simple-minded regular expression matcher (which however does not work in all cases), and\bigskip
|
|
119 |
\item one which works provably in all cases
|
|
120 |
|
|
121 |
\begin{center}
|
|
122 |
\bl{matcher r s} \;\;if and only if \;\; \bl{s $\in$ $L$(r)}
|
|
123 |
\end{center}
|
|
124 |
\end{itemize}
|
|
125 |
|
|
126 |
\end{frame}}
|
|
127 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
128 |
|
|
129 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
130 |
\mode<presentation>{
|
|
131 |
\begin{frame}[c]
|
|
132 |
\frametitle{\begin{tabular}{c}The Derivative of a Rexp\end{tabular}}
|
|
133 |
|
|
134 |
\begin{center}
|
|
135 |
\begin{tabular}{@ {}l@ {\hspace{2mm}}c@ {\hspace{2mm}}l@ {\hspace{-10mm}}l@ {}}
|
|
136 |
\bl{der c ($\varnothing$)} & \bl{$\dn$} & \bl{$\varnothing$} & \\
|
|
137 |
\bl{der c ($\epsilon$)} & \bl{$\dn$} & \bl{$\varnothing$} & \\
|
|
138 |
\bl{der c (d)} & \bl{$\dn$} & \bl{if c $=$ d then $\epsilon$ else $\varnothing$} & \\
|
|
139 |
\bl{der c (r$_1$ + r$_2$)} & \bl{$\dn$} & \bl{(der c r$_1$) + (der c r$_2$)} & \\
|
|
140 |
\bl{der c (r$_1$ $\cdot$ r$_2$)} & \bl{$\dn$} & \bl{if nullable r$_1$}\\
|
|
141 |
& & \bl{then ((der c r$_1$) $\cdot$ r$_2$) + (der c r$_2$)}\\
|
|
142 |
& & \bl{else (der c r$_1$) $\cdot$ r$_2$}\\
|
|
143 |
\bl{der c (r$^*$)} & \bl{$\dn$} & \bl{(der c r) $\cdot$ (r$^*$)}\\
|
|
144 |
\end{tabular}
|
|
145 |
\end{center}
|
|
146 |
|
|
147 |
``the regular expression after \bl{c} has been recognised''
|
|
148 |
|
|
149 |
\end{frame}}
|
|
150 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
151 |
|
|
152 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
153 |
\mode<presentation>{
|
|
154 |
\begin{frame}[c]
|
|
155 |
|
|
156 |
For this we defined the set \bl{Der c A} as
|
|
157 |
|
|
158 |
\begin{center}
|
|
159 |
\bl{Der c A $\dn$ $\{$ s $|$ c::s $\in$ A$\}$ }
|
|
160 |
\end{center}
|
|
161 |
|
|
162 |
which is called the semantic derivative of a set
|
|
163 |
and proved
|
|
164 |
|
|
165 |
\begin{center}
|
|
166 |
\bl{$L$(der c r) $=$ Der c ($L$(r))}
|
|
167 |
\end{center}
|
|
168 |
|
|
169 |
|
|
170 |
\end{frame}}
|
|
171 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
172 |
|
|
173 |
|
|
174 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
175 |
\mode<presentation>{
|
|
176 |
\begin{frame}[c]
|
|
177 |
\frametitle{\begin{tabular}{c}The Idea of the Algorithm\end{tabular}}
|
|
178 |
|
|
179 |
If we want to recognise the string \bl{abc} with regular expression \bl{r}
|
|
180 |
then\medskip
|
|
181 |
|
|
182 |
\begin{enumerate}
|
|
183 |
\item \bl{Der a ($L$(r))}\pause
|
|
184 |
\item \bl{Der b (Der a ($L$(r)))}
|
|
185 |
\item \bl{Der c (Der b (Der a ($L$(r))))}\pause
|
|
186 |
\item finally we test whether the empty string is in set\pause\medskip
|
|
187 |
\end{enumerate}
|
|
188 |
|
|
189 |
The matching algorithm works similarly, just over regular expression than sets.
|
|
190 |
\end{frame}}
|
|
191 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
192 |
|
|
193 |
|
|
194 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
195 |
\mode<presentation>{
|
|
196 |
\begin{frame}[c]
|
|
197 |
|
|
198 |
Input: string \bl{abc} and regular expression \bl{r}
|
|
199 |
|
|
200 |
\begin{enumerate}
|
|
201 |
\item \bl{der a r}
|
|
202 |
\item \bl{der b (der a r)}
|
|
203 |
\item \bl{der c (der b (der a r))}\pause
|
|
204 |
\item finally check whether the latter regular expression can match the empty string
|
|
205 |
\end{enumerate}
|
|
206 |
|
|
207 |
\end{frame}}
|
|
208 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
209 |
|
|
210 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
211 |
\mode<presentation>{
|
|
212 |
\begin{frame}[c]
|
|
213 |
|
|
214 |
We need to prove
|
|
215 |
|
|
216 |
\begin{center}
|
|
217 |
\bl{$L$(der c r) $=$ Der c ($L$(r))}
|
|
218 |
\end{center}
|
|
219 |
|
|
220 |
by induction on the regular expression.
|
|
221 |
|
|
222 |
\end{frame}}
|
|
223 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
224 |
|
|
225 |
|
|
226 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
227 |
\mode<presentation>{
|
|
228 |
\begin{frame}[c]
|
|
229 |
\frametitle{\begin{tabular}{c}Proofs about Rexp\end{tabular}}
|
|
230 |
|
|
231 |
\begin{itemize}
|
|
232 |
\item \bl{$P$} holds for \bl{$\varnothing$}, \bl{$\epsilon$} and \bl{c}\bigskip
|
|
233 |
\item \bl{$P$} holds for \bl{r$_1$ + r$_2$} under the assumption that \bl{$P$} already
|
|
234 |
holds for \bl{r$_1$} and \bl{r$_2$}.\bigskip
|
|
235 |
\item \bl{$P$} holds for \bl{r$_1$ $\cdot$ r$_2$} under the assumption that \bl{$P$} already
|
|
236 |
holds for \bl{r$_1$} and \bl{r$_2$}.
|
|
237 |
\item \bl{$P$} holds for \bl{r$^*$} under the assumption that \bl{$P$} already
|
|
238 |
holds for \bl{r}.
|
|
239 |
\end{itemize}
|
|
240 |
|
|
241 |
\end{frame}}
|
|
242 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
243 |
|
|
244 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
245 |
\mode<presentation>{
|
|
246 |
\begin{frame}[c]
|
|
247 |
\frametitle{\begin{tabular}{c}Proofs about Natural Numbers\\ and Strings\end{tabular}}
|
|
248 |
|
|
249 |
\begin{itemize}
|
|
250 |
\item \bl{$P$} holds for \bl{$0$} and
|
|
251 |
\item \bl{$P$} holds for \bl{$n + 1$} under the assumption that \bl{$P$} already
|
|
252 |
holds for \bl{$n$}
|
|
253 |
\end{itemize}\bigskip
|
|
254 |
|
|
255 |
\begin{itemize}
|
|
256 |
\item \bl{$P$} holds for \bl{\texttt{""}} and
|
|
257 |
\item \bl{$P$} holds for \bl{$c\!::\!s$} under the assumption that \bl{$P$} already
|
|
258 |
holds for \bl{$s$}
|
|
259 |
\end{itemize}
|
|
260 |
|
|
261 |
\end{frame}}
|
|
262 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
263 |
|
|
264 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
265 |
\mode<presentation>{
|
|
266 |
\begin{frame}[t]
|
|
267 |
\frametitle{\begin{tabular}{c}Regular Expressions\end{tabular}}
|
|
268 |
|
|
269 |
\begin{center}
|
|
270 |
\begin{tabular}{@ {}rrl@ {\hspace{13mm}}l}
|
|
271 |
\bl{r} & \bl{$::=$} & \bl{$\varnothing$} & null\\
|
|
272 |
& \bl{$\mid$} & \bl{$\epsilon$} & empty string / "" / []\\
|
|
273 |
& \bl{$\mid$} & \bl{c} & character\\
|
|
274 |
& \bl{$\mid$} & \bl{r$_1$ $\cdot$ r$_2$} & sequence\\
|
|
275 |
& \bl{$\mid$} & \bl{r$_1$ + r$_2$} & alternative / choice\\
|
|
276 |
& \bl{$\mid$} & \bl{r$^*$} & star (zero or more)\\
|
|
277 |
\end{tabular}\bigskip\pause
|
|
278 |
\end{center}
|
|
279 |
|
|
280 |
\end{frame}}
|
|
281 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
282 |
|
|
283 |
|
|
284 |
|
|
285 |
|
|
286 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
287 |
\mode<presentation>{
|
|
288 |
\begin{frame}[c]
|
|
289 |
\frametitle{\begin{tabular}{c}Languages\end{tabular}}
|
|
290 |
|
|
291 |
A \alert{language} is a set of strings.\bigskip
|
|
292 |
|
|
293 |
A \alert{regular expression} specifies a set of strings or language.\bigskip
|
|
294 |
|
|
295 |
A language is \alert{regular} iff there exists
|
|
296 |
a regular expression that recognises all its strings.\bigskip\bigskip\pause
|
|
297 |
|
|
298 |
\textcolor{gray}{not all languages are regular, e.g.~\bl{a$^n$b$^n$}.}
|
|
299 |
\end{frame}}
|
|
300 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
301 |
|
|
302 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
303 |
\mode<presentation>{
|
|
304 |
\begin{frame}[t]
|
|
305 |
\frametitle{\begin{tabular}{c}Regular Expressions\end{tabular}}
|
|
306 |
|
|
307 |
\begin{center}
|
|
308 |
\begin{tabular}{@ {}rrl@ {\hspace{13mm}}l}
|
|
309 |
\bl{r} & \bl{$::=$} & \bl{$\varnothing$} & null\\
|
|
310 |
& \bl{$\mid$} & \bl{$\epsilon$} & empty string / "" / []\\
|
|
311 |
& \bl{$\mid$} & \bl{c} & character\\
|
|
312 |
& \bl{$\mid$} & \bl{r$_1$ $\cdot$ r$_2$} & sequence\\
|
|
313 |
& \bl{$\mid$} & \bl{r$_1$ + r$_2$} & alternative / choice\\
|
|
314 |
& \bl{$\mid$} & \bl{r$^*$} & star (zero or more)\\
|
|
315 |
\end{tabular}\bigskip
|
|
316 |
\end{center}
|
|
317 |
|
|
318 |
How about ranges \bl{[a-z]}, \bl{r$^\text{+}$} and \bl{!r}?
|
|
319 |
|
|
320 |
\end{frame}}
|
|
321 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
322 |
|
|
323 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
324 |
\mode<presentation>{
|
|
325 |
\begin{frame}[c]
|
|
326 |
\frametitle{\begin{tabular}{c}Negation of Regular Expr's\end{tabular}}
|
|
327 |
|
|
328 |
\begin{itemize}
|
|
329 |
\item \bl{!r} \hspace{6mm} (everything that \bl{r} cannot recognise)\medskip
|
|
330 |
\item \bl{$L$(!r) $\dn$ UNIV - $L$(r)}\medskip
|
|
331 |
\item \bl{nullable (!r) $\dn$ not (nullable(r))}\medskip
|
|
332 |
\item \bl{der\,c\,(!r) $\dn$ !(der\,c\,r)}
|
|
333 |
\end{itemize}
|
|
334 |
|
|
335 |
\end{frame}}
|
|
336 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
337 |
|
|
338 |
|
|
339 |
|
|
340 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
341 |
\mode<presentation>{
|
|
342 |
\begin{frame}[c]
|
|
343 |
\frametitle{\begin{tabular}{c}Regular Exp's for Lexing\end{tabular}}
|
|
344 |
|
|
345 |
Lexing separates strings into ``words'' / components.
|
|
346 |
|
|
347 |
\begin{itemize}
|
|
348 |
\item Identifiers (non-empty strings of letters or digits, starting with a letter)
|
|
349 |
\item Numbers (non-empty sequences of digits omitting leading zeros)
|
|
350 |
\item Keywords (else, if, while, \ldots)
|
|
351 |
\item White space (a non-empty sequence of blanks, newlines and tabs)
|
|
352 |
\item Comments
|
|
353 |
\end{itemize}
|
|
354 |
|
|
355 |
\end{frame}}
|
|
356 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
357 |
|
|
358 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
359 |
\mode<presentation>{
|
|
360 |
\begin{frame}[c]
|
|
361 |
\frametitle{\begin{tabular}{c}Automata\end{tabular}}
|
|
362 |
|
|
363 |
A deterministic finite automaton consists of:
|
|
364 |
|
|
365 |
\begin{itemize}
|
|
366 |
\item a set of states
|
|
367 |
\item one of these states is the start state
|
|
368 |
\item some states are accepting states, and
|
|
369 |
\item there is transition function\medskip
|
|
370 |
|
|
371 |
\small
|
|
372 |
which takes a state as argument and a character and produces a new state\smallskip\\
|
|
373 |
this function might not always be defined
|
|
374 |
\end{itemize}
|
|
375 |
|
|
376 |
\end{frame}}
|
|
377 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
378 |
|
|
379 |
|
|
380 |
\end{document}
|
|
381 |
|
|
382 |
%%% Local Variables:
|
|
383 |
%%% mode: latex
|
|
384 |
%%% TeX-master: t
|
|
385 |
%%% End:
|
|
386 |
|