(*<*)
theory Slides4
imports "../CpsG" "../ExtGG" "~~/src/HOL/Library/LaTeXsugar"
begin
notation (latex output)
set ("_") and
Cons ("_::/_" [66,65] 65)
(*
ML {*
open Printer;
show_question_marks_default := false;
*}
*)
notation (latex output)
Cons ("_::_" [78,77] 73) and
vt ("valid'_state") and
runing ("running") and
birthtime ("last'_set") and
If ("(\<^raw:\textrm{>if\<^raw:}> (_)/ \<^raw:\textrm{>then\<^raw:}> (_)/ \<^raw:\textrm{>else\<^raw:}> (_))" 10) and
Prc ("'(_, _')") and
holding ("holds") and
waiting ("waits") and
Th ("T") and
Cs ("C") and
P ("Lock") and
V ("Unlock") and
readys ("ready") and
depend ("RAG") and
preced ("prec") and
cpreced ("cprec") and
dependents ("dependants") and
cp ("cprec") and
holdents ("resources") and
original_priority ("priority") and
DUMMY ("\<^raw:\mbox{$\_\!\_$}>")
(*>*)
text_raw {*
\renewcommand{\slidecaption}{NASA, 20 June 2013}
\newcommand{\bl}[1]{#1}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}
\frametitle{%
\begin{tabular}{@ {}c@ {}}
\\[-3mm]
\LARGE Formalisations and the\\[-1mm]
\LARGE Isabelle Theorem Prover\\[-3mm]
\end{tabular}}
\begin{center}
Christian Urban\\[1mm]
\small King's College London
\end{center}\bigskip
\begin{center}
many thanks to Mahyar Malekpour and Cesar Munoz for the invitation and
hospitality
\end{center}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}<2->[c]
\frametitle{Isabelle Theorem Prover}
\begin{center}
\includegraphics[scale=0.23]{isabelle.png}
\end{center}
\only<2>{
\begin{textblock}{12}(2,13.6)
\begin{tikzpicture}
\draw (0,0) node[inner sep=2mm,fill=cream, ultra thick, draw=red, rounded corners=2mm]
{\normalsize\color{darkgray}
\begin{minipage}{9cm}\raggedright
\ldots to make sure large proofs are correct
\end{minipage}};
\end{tikzpicture}
\end{textblock}}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
\tikzstyle{every node}=[node distance=25mm,text height=1.5ex, text depth=.25ex]
\tikzstyle{node1}=[rectangle, minimum size=8mm, rounded corners=3mm, very thick,
draw=black!50, top color=white, bottom color=black!20]
\tikzstyle{node2}=[rectangle, minimum size=10mm, rounded corners=3mm, very thick,
draw=red!70, top color=white, bottom color=red!50!black!20]
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{}
\begin{tabular}{@ {}c@ {\hspace{2mm}}c}
\\[6mm]
\begin{tabular}{c}
\includegraphics[scale=0.11]{harper.jpg}\\[-2mm]
{\footnotesize Bob Harper}\\[-2.5mm]
{\footnotesize (CMU)}
\end{tabular}
\begin{tabular}{c@ {}}
\includegraphics[scale=0.37]{pfenning.jpg}\\[-2mm]
{\footnotesize Frank Pfenning}\\[-2.5mm]
{\footnotesize (CMU)}
\end{tabular} &
\begin{tabular}{@ {\hspace{-3mm}}p{7cm}}
\begin{tikzpicture}[remember picture, scale=0.5]
\matrix[ampersand replacement=\&,column sep=7mm, row sep=5mm]
{ \& \& \node (desc) {\makebox[0mm]{\begin{tabular}{l}published in a journal\\
\small (ACM ToCL, 31 pages, 2005)\\[3mm]\end{tabular}}};\\
\&[-10mm]
\node (def1) [node1] {\hspace{1mm}Spec\hspace{1mm}\mbox{}}; \&
\node (proof1) [node1] {Proof}; \&
\node (alg1) [node1] {\hspace{1mm}Alg\hspace{1mm}\mbox{}}; \\
};
\draw[->,black!50,line width=2mm] (proof1) -- (def1);
\draw[->,black!50,line width=2mm] (proof1) -- (alg1);
\draw[<-,black,line width=0.5mm] (proof1) -- (desc);
\end{tikzpicture}
\end{tabular}\\
\pause
\\[0mm]
\multicolumn{2}{c}{
\begin{tabular}{p{6cm}}
\raggedright
\color{black}{relied on their proof in a\\ {\bf security} critical application}
\end{tabular}
\begin{tabular}{c}
\includegraphics[scale=0.36]{appel.jpg}\\[-2mm]
{\footnotesize Andrew Appel}\\[-2.5mm]
{\footnotesize (Princeton)}
\end{tabular}}
\end{tabular}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}<4->
\frametitle{\LARGE\begin{tabular}{c}An Example for a Small TCB\end{tabular}}
\mbox{}\\[-14mm]\mbox{}
\begin{columns}
\begin{column}{0.2\textwidth}
\begin{tabular}{@ {} c@ {}}
\includegraphics[scale=0.3]{appel.jpg}\\[-2mm]
{\footnotesize Andrew Appel}\\[-2.5mm]
{\footnotesize (Princeton)}
\end{tabular}
\end{column}
\begin{column}{0.8\textwidth}
\begin{textblock}{10}(4.5,3.95)
\begin{block}{Proof-Carrying Code:}
\begin{center}
\begin{tikzpicture}
\draw[help lines,cream] (0,0.2) grid (8,4);
\draw[line width=1mm, red] (5.5,0.6) rectangle (7.5,4);
\node[anchor=base] at (6.5,2.8)
{\small\begin{tabular}{@ {}p{1.9cm}@ {}}\centering user can run untrusted code\end{tabular}};
\draw[line width=1mm, red] (0.5,0.6) rectangle (2.5,4);
\node[anchor=base] at (1.5,2.3)
{\small\begin{tabular}{@ {}p{1.9cm}@ {}}\centering code developer/ web server/ Apple
Store\end{tabular}};
\onslide<4->{
\draw[line width=1mm, red, fill=red] (5.5,0.6) rectangle (7.5,1.8);
\node[anchor=base,white] at (6.5,1.1)
{\small\begin{tabular}{@ {}p{1.9cm}@ {}}\bf\centering proof- checker\end{tabular}};}
\node at (3.8,3.0) [single arrow, fill=red,text=white, minimum height=3cm]{\bf code};
\onslide<3->{
\node at (3.8,1.3) [single arrow, fill=red,text=white, minimum height=3cm]{\bf LF proof};
\node at (3.8,1.9) {\small certificate};
}
\onslide<2>{\node at (4.0,1.3) [text=red]{\begin{tabular}{c}\bf Highly\\\bf Dangerous!\end{tabular}};}
% Code Developer
% User (runs untrusted code)
% transmits a proof that the code is safe
%
\end{tikzpicture}
\end{center}
\end{block}
\end{textblock}
\end{column}
\end{columns}
\small\mbox{}\\[3.2cm]
\begin{itemize}
\item<4-> TCB of the checker is $\sim$2700 lines of code (1865 loc of\\ LF definitions;
803 loc in C including 2 library functions)\\[-3mm]
\item<4-> 167 loc in C implement a type-checker
\end{itemize}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
\tikzstyle{every node}=[node distance=25mm,text height=1.5ex, text depth=.25ex]
\tikzstyle{node1}=[rectangle, minimum size=10mm, rounded corners=3mm, very thick,
draw=black!50, top color=white, bottom color=black!20]
\tikzstyle{node2}=[rectangle, minimum size=12mm, rounded corners=3mm, very thick,
draw=red!70, top color=white, bottom color=red!50!black!20]
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}<2->[squeeze]
\frametitle{}
\begin{columns}
\begin{column}{0.8\textwidth}
\begin{textblock}{0}(1,2)
\begin{tikzpicture}
\matrix[ampersand replacement=\&,column sep=7mm, row sep=5mm]
{ \&[-10mm]
\node (def1) [node1] {\large\hspace{1mm}Spec\hspace{1mm}\mbox{}}; \&
\node (proof1) [node1] {\large Proof}; \&
\node (alg1) [node1] {\large\hspace{1mm}Alg\hspace{1mm}\mbox{}}; \\
\onslide<4->{\node {\begin{tabular}{c}\small 1st\\[-2.5mm] \footnotesize solution\end{tabular}};} \&
\onslide<4->{\node (def2) [node2] {\large Spec$^\text{+ex}$};} \&
\onslide<4->{\node (proof2) [node1] {\large Proof};} \&
\onslide<4->{\node (alg2) [node1] {\large\hspace{1mm}Alg\hspace{1mm}\mbox{}};} \\
\onslide<5->{\node {\begin{tabular}{c}\small 2nd\\[-2.5mm] \footnotesize solution\end{tabular}};} \&
\onslide<5->{\node (def3) [node1] {\large\hspace{1mm}Spec\hspace{1mm}\mbox{}};} \&
\onslide<5->{\node (proof3) [node1] {\large Proof};} \&
\onslide<5->{\node (alg3) [node2] {\large Alg$^\text{-ex}$};} \\
\onslide<6->{\node {\begin{tabular}{c}\small 3rd\\[-2.5mm] \footnotesize solution\end{tabular}};} \&
\onslide<6->{\node (def4) [node1] {\large\hspace{1mm}Spec\hspace{1mm}\mbox{}};} \&
\onslide<6->{\node (proof4) [node2] {\large\hspace{1mm}Proof\hspace{1mm}};} \&
\onslide<6->{\node (alg4) [node1] {\large\hspace{1mm}Alg\hspace{1mm}\mbox{}};} \\
};
\draw[->,black!50,line width=2mm] (proof1) -- (def1);
\draw[->,black!50,line width=2mm] (proof1) -- (alg1);
\onslide<4->{\draw[->,black!50,line width=2mm] (proof2) -- (def2);}
\onslide<4->{\draw[->,black!50,line width=2mm] (proof2) -- (alg2);}
\onslide<5->{\draw[->,black!50,line width=2mm] (proof3) -- (def3);}
\onslide<5->{\draw[->,black!50,line width=2mm] (proof3) -- (alg3);}
\onslide<6->{\draw[->,black!50,line width=2mm] (proof4) -- (def4);}
\onslide<6->{\draw[->,black!50,line width=2mm] (proof4) -- (alg4);}
\onslide<3->{\draw[white,line width=1mm] (1.1,3.2) -- (0.9,2.85) -- (1.1,2.35) -- (0.9,2.0);}
\end{tikzpicture}
\end{textblock}
\end{column}
\end{columns}
\begin{textblock}{3}(12,3.6)
\onslide<4->{
\begin{tikzpicture}
\node at (0,0) [single arrow, shape border rotate=270, fill=red,text=white]{2h};
\end{tikzpicture}}
\end{textblock}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{Other Formalisations}
\begin{itemize}
\item I also found a (fixable) mistake in my PhD thesis\bigskip
\item Nominal Isabelle: found out that the variable convention
can be used to prove false (a surprising result in PL-research)\bigskip
\item Computability and Logic Book (5th ed.)\\ by Boolos, Burgess and Jeffrey ---
two definitions about halting computations in UTMs are inconsistent
\end{itemize}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{Scheduling in RTOS}
\begin{itemize}
\item RTOS: priorities and resource locking
\item Purpose:\\
guarantee tasks to be completed in time\medskip\pause
\item \alert{this already results into a surprisingly non-trivial algorithmic problem}
\end{itemize}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{The Problem}
\Large
\begin{center}
\begin{tabular}{l}
\alert{H}igh-priority process (waits)\\[4mm]
\onslide<2->{\alert{M}edium-priority process}\\[4mm]
\alert{L}ow-priority process (has a lock)\\[4mm]
\end{tabular}
\end{center}
\onslide<3->{
\begin{itemize}
\item \alert{priority inversion}\\ \hspace{2cm}@{text "\<equiv>"} H waits for a process\\
\mbox{}\hfill with lower priority
\item<4> avoid \alert{indefinite} priority inversion
\end{itemize}}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{Mars Pathfinder Mission 1997}
\large
\begin{center}
\includegraphics[scale=0.15]{marspath1.png}
\includegraphics[scale=0.16]{marspath3.png}
\includegraphics[scale=0.3]{marsrover.png}
\end{center}
\begin{itemize}
\item the lander reset frequently on Mars
\item the problem: priority inversion
\end{itemize}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{The Solution}
\Large
\alert{Priority Inheritance Protocol (PIP):}\bigskip
\begin{center}
\begin{tabular}{l}
\alert{H}igh-priority process\\[4mm]
\textcolor{gray}{Medium-priority process}\\[4mm]
\alert{L}ow-priority process\\[15mm]
{\normalsize (temporarily raise the priority of \alert{L})}
\end{tabular}
\end{center}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{A First Correctness ``Proof''}
\Large
\begin{itemize}
\item the paper$^\star$ first describing PIP ``proved'' also its
correctness:\\[5mm]
\end{itemize}
\normalsize
\begin{quote}
\ldots{}after the thread (whose priority has been raised) completes its
critical section and releases the lock, it ``returns to its original
priority level''.
\end{quote}\bigskip
\small
$^\star$ in IEEE Transactions on Computers in 1990 by Sha et al.
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{}
\Large
\begin{center}
\begin{tabular}{l}
\alert{H}igh-priority process 1 (waits)\\[2mm]
\alert{H}igh-priority process 2 (waits)\\[8mm]
\alert{L}ow-priority process (has a lock)
\end{tabular}
\end{center}
\onslide<2->{
\begin{itemize}
\item Solution: return to the highest
\phantom{Solution:} \alert{remaining} priority\\
\end{itemize}}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{Specification}
\Large
\begin{itemize}\Large
\item Use Inductive Method with events of the form:
\end{itemize}
\begin{center}
\begin{tabular}{l}
Create \textcolor{gray}{thread priority}\\
Exit \textcolor{gray}{thread}\\
Set \textcolor{gray}{thread priority}\\
Lock \textcolor{gray}{thread cs}\\
Unlock \textcolor{gray}{thread cs}\\
\end{tabular}
\end{center}\medskip
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{Scheduling States}
\Large
\begin{itemize}
\item A \alert{state s} is a list of events\bigskip
\begin{center}
\begin{tikzpicture}
\draw [->, line width=1.5mm] (-4,0) -- (4, 0);
\draw [line width=0.8mm] (-4, 0.3) -- (-4, -0.3);
\draw [line width=0.8mm] (1, 0.3) -- (1, -0.3);
\node at (1,-0.7) {\large s};
\node at (-4,-0.7) {\large 0};
\node at (3.2,-0.7) {\large time};
\end{tikzpicture}
\end{center}\pause
\item Scheduling according to \alert{precedences}:
\begin{center}
\begin{tabular}{@ {}l@ {}}
\large @{thm preced_def[where thread="th"]}
\end{tabular}
\end{center}
\end{itemize}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{Waiting Queues}
\large
\begin{itemize}
\item A \alert{waiting queue} function returns a list of threads
associated with every resource
\item The head of the list is the thread holding the resource.
\medskip
\begin{center}\normalsize
\begin{tabular}{@ {}l}
@{thm cs_holding_def[where thread="th"]}\\
@{thm cs_waiting_def[where thread="th"]}
\end{tabular}
\end{center}
\end{itemize}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{Resource Allocation Graphs}
\begin{center}
\newcommand{\fnt}{\fontsize{7}{8}\selectfont}
\begin{tikzpicture}[scale=1]
\node (A) at (0,0) [draw, rounded corners=1mm, rectangle, very thick] {@{text "th\<^isub>0"}};
\node (B) at (2,0) [draw, circle, very thick, inner sep=0.4mm] {@{text "cs\<^isub>1"}};
\node (C) at (4,0.7) [draw, rounded corners=1mm, rectangle, very thick] {@{text "th\<^isub>1"}};
\node (D) at (4,-0.7) [draw, rounded corners=1mm, rectangle, very thick] {@{text "th\<^isub>2"}};
\node (E) at (6,-0.7) [draw, circle, very thick, inner sep=0.4mm] {@{text "cs\<^isub>2"}};
\node (E1) at (6, 0.3) [draw, circle, very thick, inner sep=0.4mm] {@{text "cs\<^isub>3"}};
\node (F) at (8,-0.7) [draw, rounded corners=1mm, rectangle, very thick] {@{text "th\<^isub>3"}};
\draw [<-,line width=0.6mm] (A) to node [pos=0.54,sloped,above=-0.5mm] {\fnt{}holds} (B);
\draw [->,line width=0.6mm] (C) to node [pos=0.4,sloped,above=-0.5mm] {\fnt{}waits} (B);
\draw [->,line width=0.6mm] (D) to node [pos=0.4,sloped,below=-0.5mm] {\fnt{}waits} (B);
\draw [<-,line width=0.6mm] (D) to node [pos=0.54,sloped,below=-0.5mm] {\fnt{}holds} (E);
\draw [<-,line width=0.6mm] (D) to node [pos=0.54,sloped,above=-0.5mm] {\fnt{}holds} (E1);
\draw [->,line width=0.6mm] (F) to node [pos=0.45,sloped,below=-0.5mm] {\fnt{}waits} (E);
\end{tikzpicture}
\end{center}\bigskip
\begin{center}
\begin{minipage}{0.8\linewidth}
\raggedleft
@{thm cs_depend_def}
\end{minipage}\medskip\\
\begin{minipage}{1\linewidth}
@{thm cs_dependents_def}
\end{minipage}\medskip\\\pause
\begin{minipage}{1\linewidth}
\alert{cprec wq s th} $\dn$\\
\mbox{}\hspace{1cm}Max(\{prec th s\} $\cup$\\
\mbox{}\hspace{1cm}\phantom{Max(}\{prec th' s $\mid$ th' $\in$ dependants wq th\})
\end{minipage}
\end{center}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{The Scheduler}
\large
\begin{itemize}
\item \underline{Start}: all priorities/precedences are 0, all resources are unlocked
\item \underline{Create th p}: set precedence of th
\item \underline{Exit th}: reset precedence to 0
\item \underline{Set th p}: reset precedence of th
\item \underline{Lock th cs}: add th to the end of the waiting queue of cs
\item \underline{Unlock th cs}:\\ delete th from the waiting queue of cs\\
\hspace{1cm}\alert{and who to give the resource next?}
\end{itemize}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{The Scheduler (2)}
%%\large
\begin{itemize}
\item \large threads ready to run\normalsize
\begin{center}
\begin{tabular}{@ {}l}
@{thm (lhs) readys_def} $\dn$\\
\;@{thm (rhs) readys_def}
\end{tabular}
\end{center}\bigskip
\item \large the thread that is running in a state:\\[-10mm]\normalsize
\begin{center}
\begin{tabular}{@ {}l@ {}}
@{thm (lhs) runing_def} $\dn$\\
\;@{thm (rhs) runing_def}
\end{tabular}
\end{center}
\end{itemize}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{Inductive Method}
%%\large
\begin{center}
\begin{tikzpicture}[scale=1.6]
%%\draw[step=2mm] (-4,-1) grid (4,1.4);
\draw (0,0.2) node {\begin{tabular}{l} valid\\[-1mm] scheduler\\[-1mm] states\\ \end{tabular}};
\draw (3,0) node {\begin{tabular}{l} set of invalid\\[-1mm] scheduler states \\[-1mm](e.g., deadlocks)\\ \end{tabular}};
\draw[<-, line width=0.5mm] (1.0,0) -- (1.8,0);
\draw[<-, line width=0.5mm] (-0.2,-0.55) -- (-0.4,-1.3);
\draw (-0.0,-1.5) node {\begin{tabular}{l} inductively defined set \end{tabular}};
\draw[line width=0.5mm, rounded corners=6.3pt]
(-0.9,-0.05) -- (-0.8,0.6) -- (-0.3,0.95) -- (0,1) -- (0.5,0.8) -- (0.65,0.5) -- (0.7,0) -- (0.4,-0.5) -- (0,-0.6) -- (-0.5,-0.45) -- cycle;
\draw[line width=0.5mm, rounded corners=15pt]
(-1.2,0) -- (-0.9,0.95) -- (0,1.2) -- (1.0,1.0) -- (1.7,0) -- (0.95,-1.0) -- (0,-1.2) -- (-0.9,-0.9) -- cycle;
\end{tikzpicture}
\end{center}
\begin{itemize}
\item We have to exclude situations where there is a deadlock,
a thread exited before created, \ldots
\end{itemize}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{Valid Next Events}
\large
\begin{itemize}
\item In a state s, the following events can occur:
\end{itemize}
\begin{center}
@{thm[mode=Rule] thread_create[where thread=th]}\bigskip
@{thm[mode=Rule] thread_exit[where thread=th]}\bigskip
@{thm[mode=Rule] thread_set[where thread=th]}
\end{center}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{Valid Next Events (2)}
\large
\begin{center}
@{thm[mode=Rule] thread_P[where thread=th]}\bigskip
@{thm[mode=Rule] thread_V[where thread=th]}\bigskip
\end{center}\bigskip\pause
\begin{itemize}
\item Done with the specification. \ldots
\end{itemize}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{Correctness Criterion}
\large
\begin{center}
\begin{tikzpicture}
\draw [->, line width=1.5mm] (-4,0) -- (4, 0);
\draw [line width=0.8mm] (-4, 0.3) -- (-4, -0.3);
\draw [line width=0.8mm] (1, 0.3) -- (1, -0.3);
\draw [line width=0.8mm] (0, 0.3) -- (0, -0.3);
\node at (1,-0.7) {\large s'};
\node at (0,-0.7) {\large s};
\node at (1,-1.5) {\small(th')};
\node at (0,-1.5) {\small(th)};
\node at (-4,-0.7) {\large 0};
\node at (3.2,-0.7) {\large time};
\end{tikzpicture}
\end{center}
\normalsize
\begin{itemize}
\item {\bf If} th is alive in s and has the highest precedence
\item plus some further assumption (like th not reset, not exited, no higher precedences in s - s')
\item and th is {\bf not} running in s', \\ {\bf then} the running
thread th' (in s') is a thread that was alive in {\bf s} and has in s' the same
precedence as th in s.
\end{itemize}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
(*<*)
context extend_highest_gen
begin
(*>*)
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[t]
\frametitle{Implementation}
\begin{itemize}
\item Create/Exit events:
\begin{itemize}
\item we do not have to recalculate the RAG
\item we do not have to recalculate the other precedences
\end{itemize}\bigskip
\item Set event:
\begin{itemize}
\item we do not have to recalculate the RAG
\item also the other precedences do not have to be recalculated
(since this is the currently running thread, it cannot affect
other threads)
\end{itemize}
\item Unlock event (2 cases: a thread to take over, no thread to take over)
\begin{itemize}
\item case 1: RAG needs to be modified, but apart from th and th' no
other precedence needs to be recalculated
\item case 2: RAG needs to be prunned, no precedence needs to be recalculated
\end{itemize}
\end{itemize}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[t]
\frametitle{Implementation (2)}
\begin{itemize}
\item Unlock event (2 cases: a thread to take over, no thread to take over)
\begin{itemize}
\item case 1: RAG needs to be modified, but apart from th and th' no
other precedence needs to be recalculated
\item case 2: RAG needs to be pruned, no precedence needs to be recalculated
\end{itemize}\bigskip
\item Lock event (2 cases: cs is locked, not locked)
\begin{itemize}
\item case 1: a waiting edge needs to be added to the RAG, precedences of
all dependants need to recalculated (where there is a change)
\item case 2: a holding edge needs to be added to the RAG, no
precedences need to be recalculated
\end{itemize}
\end{itemize}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{Implementation}
\begin{itemize}
\item in PINTOS (Stanford), written in C for educational purposes\bigskip
\begin{center}
\begin{tabular}{|l@ {\hspace{2mm}}|l@ {\hspace{2mm}}|}
\hline
{\bf Event} & {\bf PINTOS function} \\
\hline
@{text Create} & @{text "thread_create"}\\
@{text Exit} & @{text "thread_exit"}\\
@{text Set} & @{text "thread_set_priority"}\\
@{text Lock} & @{text "lock_acquire"}\\
@{text Unlock} & @{text "lock_release"}\\
\hline
\end{tabular}
\end{center}\pause\bigskip
\item \alert{We did not verify our C-code!}\pause
\item We were much faster: we gave an unlocked resource to
the thread with the highest precedence
\end{itemize}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{A Step Back\ldots}
\large
\begin{itemize}
\item Did we make any impact? No!\medskip\pause
\item real-time scheduling on multiprocessors seems to be a very
underdeveloped area
\item implementations exist, e.g.~RT-Linux
\end{itemize}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{Theorem Provers}
\begin{itemize}
\item We found a mistake in a refereed paper by Harper \& Pfenning
\item I also found a mistake in my PhD thesis
\item also a popular textbook book on Computability contained an
error\bigskip
\item scratching on the surface of an completely ``alien'' subject
to us --- we were able to make progress
\end{itemize}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{Inductive Method / Protocols}
\begin{itemize}
\item the inductive method was developed/used by Larry Paulson
for verifying security protocols\bigskip\bigskip
\item we used it for a different `kind' of protocols (scheduling)
\item but this was restricted to only single-processors, no timing information
\end{itemize}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{Clock Synchronisation}
\begin{itemize}
\item Mahyar Malekpour introduced a distributed clock-synchronisation
algorithm\\ (perfect example for us)\bigskip\bigskip
\item connected units exchange messages according to a protocol
and reach a stable, synchronised state
\item messages have to reach the receiver within a time-window\pause
\item \alert{verification still ongoing}
\end{itemize}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
text_raw {*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{Questions?}
\begin{itemize} \large
\item Thank you for the invitation and for listening!
\end{itemize}
\begin{center}
\begin{tabular}{c}
\includegraphics[scale=0.13]{isabelle.png}\\[-2mm]
\small\url{http://isabelle.in.tum.de}
\end{tabular}
\end{center}
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*}
(*<*)
end
end
(*>*)