--- a/thys2/Paper/Paper.thy Tue Jan 25 13:12:50 2022 +0000
+++ b/thys2/Paper/Paper.thy Thu Jan 27 23:25:26 2022 +0000
@@ -7,7 +7,164 @@
"../SizeBound4"
"HOL-Library.LaTeXsugar"
begin
+
+declare [[show_question_marks = false]]
+
+abbreviation
+ "der_syn r c \<equiv> der c r"
+
+notation (latex output)
+ der_syn ("_\\_" [79, 1000] 76) and
+
+ ZERO ("\<^bold>0" 81) and
+ ONE ("\<^bold>1" 81) and
+ CH ("_" [1000] 80) and
+ ALT ("_ + _" [77,77] 78) and
+ SEQ ("_ \<cdot> _" [77,77] 78) and
+ STAR ("_\<^sup>\<star>" [79] 78)
+
(*>*)
+
+section {* Introduction *}
+
+text {*
+
+Brzozowski \cite{Brzozowski1964} introduced the notion of the {\em
+derivative} @{term "der c r"} of a regular expression \<open>r\<close> w.r.t.\
+a character~\<open>c\<close>, and showed that it gave a simple solution to the
+problem of matching a string @{term s} with a regular expression @{term
+r}: if the derivative of @{term r} w.r.t.\ (in succession) all the
+characters of the string matches the empty string, then @{term r}
+matches @{term s} (and {\em vice versa}). The derivative has the
+property (which may almost be regarded as its specification) that, for
+every string @{term s} and regular expression @{term r} and character
+@{term c}, one has @{term "cs \<in> L(r)"} if and only if \mbox{@{term "s \<in> L(der c r)"}}.
+The beauty of Brzozowski's derivatives is that
+they are neatly expressible in any functional language, and easily
+definable and reasoned about in theorem provers---the definitions just
+consist of inductive datatypes and simple recursive functions. A
+mechanised correctness proof of Brzozowski's matcher in for example HOL4
+has been mentioned by Owens and Slind~\cite{Owens2008}. Another one in
+Isabelle/HOL is part of the work by Krauss and Nipkow \cite{Krauss2011}.
+And another one in Coq is given by Coquand and Siles \cite{Coquand2012}.
+
+If a regular expression matches a string, then in general there is more
+than one way of how the string is matched. There are two commonly used
+disambiguation strategies to generate a unique answer: one is called
+GREEDY matching \cite{Frisch2004} and the other is POSIX
+matching~\cite{POSIX,Kuklewicz,OkuiSuzuki2010,Sulzmann2014,Vansummeren2006}.
+For example consider the string @{term xy} and the regular expression
+\mbox{@{term "STAR (ALT (ALT x y) xy)"}}. Either the string can be
+matched in two `iterations' by the single letter-regular expressions
+@{term x} and @{term y}, or directly in one iteration by @{term xy}. The
+first case corresponds to GREEDY matching, which first matches with the
+left-most symbol and only matches the next symbol in case of a mismatch
+(this is greedy in the sense of preferring instant gratification to
+delayed repletion). The second case is POSIX matching, which prefers the
+longest match.
+
+
+
+\begin{figure}[t]
+\begin{center}
+\begin{tikzpicture}[scale=2,node distance=1.3cm,
+ every node/.style={minimum size=6mm}]
+\node (r1) {@{term "r\<^sub>1"}};
+\node (r2) [right=of r1]{@{term "r\<^sub>2"}};
+\draw[->,line width=1mm](r1)--(r2) node[above,midway] {@{term "der a DUMMY"}};
+\node (r3) [right=of r2]{@{term "r\<^sub>3"}};
+\draw[->,line width=1mm](r2)--(r3) node[above,midway] {@{term "der b DUMMY"}};
+\node (r4) [right=of r3]{@{term "r\<^sub>4"}};
+\draw[->,line width=1mm](r3)--(r4) node[above,midway] {@{term "der c DUMMY"}};
+\draw (r4) node[anchor=west] {\;\raisebox{3mm}{@{term nullable}}};
+\node (v4) [below=of r4]{@{term "v\<^sub>4"}};
+\draw[->,line width=1mm](r4) -- (v4);
+\node (v3) [left=of v4] {@{term "v\<^sub>3"}};
+\draw[->,line width=1mm](v4)--(v3) node[below,midway] {\<open>inj r\<^sub>3 c\<close>};
+\node (v2) [left=of v3]{@{term "v\<^sub>2"}};
+\draw[->,line width=1mm](v3)--(v2) node[below,midway] {\<open>inj r\<^sub>2 b\<close>};
+\node (v1) [left=of v2] {@{term "v\<^sub>1"}};
+\draw[->,line width=1mm](v2)--(v1) node[below,midway] {\<open>inj r\<^sub>1 a\<close>};
+\draw (r4) node[anchor=north west] {\;\raisebox{-8mm}{@{term "mkeps"}}};
+\end{tikzpicture}
+\end{center}
+\mbox{}\\[-13mm]
+
+\caption{The two phases of the algorithm by Sulzmann \& Lu \cite{Sulzmann2014},
+matching the string @{term "[a,b,c]"}. The first phase (the arrows from
+left to right) is \Brz's matcher building successive derivatives. If the
+last regular expression is @{term nullable}, then the functions of the
+second phase are called (the top-down and right-to-left arrows): first
+@{term mkeps} calculates a value @{term "v\<^sub>4"} witnessing
+how the empty string has been recognised by @{term "r\<^sub>4"}. After
+that the function @{term inj} ``injects back'' the characters of the string into
+the values.
+\label{Sulz}}
+\end{figure}
+
+
+*}
+
+section {* Background *}
+
+text {*
+ Sulzmann-Lu algorithm with inj. State that POSIX rules.
+ metion slg is correct.
+
+
+ \begin{figure}[t]
+ \begin{center}
+ \begin{tabular}{c}
+ @{thm[mode=Axiom] Posix.intros(1)}\<open>P\<close>@{term "ONE"} \qquad
+ @{thm[mode=Axiom] Posix.intros(2)}\<open>P\<close>@{term "c"}\medskip\\
+ @{thm[mode=Rule] Posix.intros(3)[of "s" "r\<^sub>1" "v" "r\<^sub>2"]}\<open>P+L\<close>\qquad
+ @{thm[mode=Rule] Posix.intros(4)[of "s" "r\<^sub>2" "v" "r\<^sub>1"]}\<open>P+R\<close>\medskip\\
+ $\mprset{flushleft}
+ \inferrule
+ {@{thm (prem 1) Posix.intros(5)[of "s\<^sub>1" "r\<^sub>1" "v\<^sub>1" "s\<^sub>2" "r\<^sub>2" "v\<^sub>2"]} \qquad
+ @{thm (prem 2) Posix.intros(5)[of "s\<^sub>1" "r\<^sub>1" "v\<^sub>1" "s\<^sub>2" "r\<^sub>2" "v\<^sub>2"]} \\\\
+ @{thm (prem 3) Posix.intros(5)[of "s\<^sub>1" "r\<^sub>1" "v\<^sub>1" "s\<^sub>2" "r\<^sub>2" "v\<^sub>2"]}}
+ {@{thm (concl) Posix.intros(5)[of "s\<^sub>1" "r\<^sub>1" "v\<^sub>1" "s\<^sub>2" "r\<^sub>2" "v\<^sub>2"]}}$\<open>PS\<close>\\
+ @{thm[mode=Axiom] Posix.intros(7)}\<open>P[]\<close>\medskip\\
+ $\mprset{flushleft}
+ \inferrule
+ {@{thm (prem 1) Posix.intros(6)[of "s\<^sub>1" "r" "v" "s\<^sub>2" "vs"]} \qquad
+ @{thm (prem 2) Posix.intros(6)[of "s\<^sub>1" "r" "v" "s\<^sub>2" "vs"]} \qquad
+ @{thm (prem 3) Posix.intros(6)[of "s\<^sub>1" "r" "v" "s\<^sub>2" "vs"]} \\\\
+ @{thm (prem 4) Posix.intros(6)[of "s\<^sub>1" "r" "v" "s\<^sub>2" "vs"]}}
+ {@{thm (concl) Posix.intros(6)[of "s\<^sub>1" "r" "v" "s\<^sub>2" "vs"]}}$\<open>P\<star>\<close>
+ \end{tabular}
+ \end{center}
+ \caption{Our inductive definition of POSIX values.}\label{POSIXrules}
+ \end{figure}
+
+
+*}
+
+section {* Bitcoded Derivatives *}
+
+text {*
+ bitcoded regexes / decoding / bmkeps
+ gets rid of the second phase (only single phase)
+ correctness
+*}
+
+
+section {* Simplification *}
+
+text {*
+ not direct correspondence with PDERs, because of example
+ problem with retrieve
+
+ correctness
+*}
+
+section {* Bound - NO *}
+
+section {* Bounded Regex / Not *}
+
+section {* Conclusion *}
+
text {*
\cite{AusafDyckhoffUrban2016}