
diff -r 09a57446696a -r c6351a96bf80 ChengsongPhdThesis/ChengsongPhDThesis.tex
--- a/ChengsongPhdThesis/ChengsongPhDThesis.tex	Mon Mar 07 12:27:27 2022 +0000
+++ b/ChengsongPhdThesis/ChengsongPhDThesis.tex	Tue Mar 08 00:50:40 2022 +0000
@@ -378,10 +378,99 @@
 
 \subsection{an improved version of bit-coded algorithm: with simp!}
 
-\subsection{a correctness proof for bitcoded}
+\subsection{a correctness proof for bitcoded algorithm}
 
 \subsection{finiteness proof }
+\subsubsection{closed form}
+We can give the derivative of regular expressions
+with respect to string a closed form with respect to simplification:
+\begin{itemize}
+\item
+closed form for sequences:
+\begin{verbatim}
+lemma seq_closed_form: shows 
+"rsimp (rders_simp (RSEQ r1 r2) s) = 
+rsimp ( RALTS ( (RSEQ (rders_simp r1 s) r2) # 
+                (map (rders r2) (vsuf s r1)) 
+              )  
+      )"
+\end{verbatim}
+where the recursive function $\textit{vsuf}$ is defined as
+\begin{verbatim}
+fun vsuf :: "char list -> rrexp -> char list list" where
+"vsuf [] _ = []"
+|"vsuf (c#cs) r1 = (if (rnullable r1) then  (vsuf cs (rder c r1)) @ [c # cs]
+                                      else  (vsuf cs (rder c r1))
+                   ) "
 
+\end{verbatim}
+\item
+closed form for stars:
+\begin{verbatim}
+lemma star_closed_form:
+  shows "rders_simp (RSTAR r0) (c#s) = 
+rsimp ( RALTS ( 
+(map (\lambda s1. RSEQ (rders_simp r0 s1) (RSTAR r0) ) 
+(star_updates s r [[c]]) ) ))"
+\end{verbatim}
+where the recursive function $\textit{star}\_\textit{updates}$ is defined as
+\begin{verbatim}
+fun star_update :: "char -> rrexp -> char list list -> char list list" where
+"star_update c r [] = []"
+|"star_update c r (s # Ss) = (if (rnullable (rders_simp r s)) 
+                                then (s@[c]) # [c] # (star_update c r Ss) 
+                               else   (s@[c]) # (star_update c r Ss) )"
+
+fun star_updates :: "char list -> rrexp -> char list list -> char list list"
+  where
+"star_updates [] r Ss = Ss"
+| "star_updates (c # cs) r Ss = star_updates cs r (star_update c r Ss)"
+
+\end{verbatim}
+
+
+\end{itemize}
+These closed form is a formalization of the intuition 
+ that we can push in the derivatives
+of compound regular expressions to its sub-expressions, and the resulting
+expression is a linear combination of those sub-expressions' derivatives.
+\subsubsection{Estimation of closed forms' size}
+And thanks to $\textit{distinctBy}$ helping with deduplication,
+the linear combination can be  bounded by the set enumerating all 
+regular expressions up to a certain size :
+\begin{verbatim}
+
+lemma star_closed_form_bounded_by_rdistinct_list_estimate:
+  shows "rsize (rsimp ( RALTS ( (map (\lambda s1. RSEQ (rders_simp r0 s1) (RSTAR r0) )
+         (star_updates s r [[c]]) ) ))) <=
+        Suc (sum_list (map rsize (rdistinct (map (\lambda s1. RSEQ (rders_simp r0 s1) (RSTAR r0) )
+         (star_updates s r [[c]]) ) {})  ) )"
+         
+         lemma distinct_list_rexp_up_to_certain_size_bouded_by_set_enumerating_up_to_that_size:
+  shows "\forallr\in set rs. (rsize r ) <= N ==> sum_list (map rsize (rdistinct rs {})) <=
+         (card (rexp_enum N))* N"
+         
+         lemma ind_hypo_on_ders_leads_to_stars_bounded:
+  shows "\foralls. rsize (rders_simp r0 s) <= N ==>        
+      (sum_list (map rsize (rdistinct (map (\lambda s1. RSEQ (rders_simp r0 s1) (RSTAR r0) )
+         (star_updates s r [[c]]) ) {})  ) ) <= 
+(card (rexp_enum (Suc (N + rsize (RSTAR r0))))) * (Suc (N + rsize (RSTAR r0)))
+"
+\end{verbatim}
+
+With the above 3 lemmas, we can argue that the inductive hypothesis
+$r_0$'s derivatives is bounded above  leads to $r_0^*$'s
+derivatives being bounded above.
+\begin{verbatim}
+
+lemma r0_bounded_star_bounded:
+  shows "\foralls. rsize (rders_simp r0 s) <= N ==>
+             \foralls. rsize (rders_simp (RSTAR r0) s) <= 
+(card (rexp_enum (Suc (N + rsize (RSTAR r0))))) * (Suc (N + rsize (RSTAR r0)))"
+\end{verbatim}
+
+
+And we have a similar argument for the sequence case.
 \subsection{stronger simplification}
 
 
@@ -401,32 +490,7 @@
 
 Deciding whether a string is in the language of the regex
 can be intuitively done by constructing an NFA\cite{Thompson_1968}:
-and simulate the running of it:
-\begin{figure}
-\centering
-\includegraphics[scale=0.5]{pics/regex_nfa_base.png}
-\end{figure}
-
-\begin{figure}
-\centering
-\includegraphics[scale=0.5]{pics/regex_nfa_seq1.png}
-\end{figure}
-
-\begin{figure}
-\centering
-\includegraphics[scale=0.5]{pics/regex_nfa_seq2.png}
-\end{figure}
-
-\begin{figure}
-\centering
-\includegraphics[scale=0.5]{pics/regex_nfa_alt.png}
-\end{figure}
-
-
-\begin{figure}
-\centering
-\includegraphics[scale=0.5]{pics/regex_nfa_star.png}
-\end{figure}
+and simulate the running of it.
 
 Which should be simple enough that modern programmers
 have no problems with it at all?
@@ -1898,6 +1962,9 @@
 analysis approach by implementing them in the same language and then compare
 their performance.
 
+
+\section{discarded}
+haha
 \bibliographystyle{plain}
 \bibliography{root,regex_time_complexity}
 




