diff -r e6d58b2a2929 -r 99880ddeae63 index.html --- a/index.html Sat Sep 07 15:04:15 2019 +0100 +++ b/index.html Fri Sep 20 11:12:38 2019 +0100 @@ -14,7 +14,6 @@ ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); - </script> </HEAD> @@ -23,12 +22,13 @@ LINK="#0000EF" VLINK="#51188E" ALINK="#FF0000"> +<font face='Tahoma'> <TABLE WIDTH="100%" BGCOLOR="#4169E1" BORDER="0" FRAME="border" - CELLPADDING="10" + CELLPADDING="11" CELLSPACING="2" RULES="all"> @@ -201,8 +201,8 @@ <TR> <TD BGCOLOR="#FFFFFF" WIDTH="75%"> <B>Nominal Isabelle</B> -I currently work on Nominal -<A HREF="http://isabelle.in.tum.de">Isabelle</A> 2. This is joint work with +I am the main developer of Nominal +<A HREF="http://isabelle.in.tum.de">Isabelle</A>. This is joint work with <A HREF="http://www21.in.tum.de/~berghofe/">Dr Stefan Berghofer</A>, <A HREF="http://sketis.net/">Dr Markus Wenzel</A>, <A HREF="http://cl-informatik.uibk.ac.at/users/cek/">Dr Cezary Kaliszyk</A>, @@ -210,22 +210,69 @@ the Isabelle-team in Munich. Many of the theoretical ideas originate from the nominal logic project - a wonderful project headed by <A HREF="http://www.cl.cam.ac.uk/~amp12/">Prof. Andrew Pitts</A>. -The aim of my work is to make formal reasoning involving binders as simple as +The aim with this work is to make formal reasoning involving binders as simple as on paper and the hope is to lure <A HREF="http://alliance.seas.upenn.edu/~plclub/cgi-bin/poplmark/index.php?title=The_POPLmark_Challenge#Vision">masses</A> to automated theorem proving. My funding for this work was provided in 2004 and 2005 by a research fellowship from the <A HREF="http://en.wikipedia.org/wiki/Alexander_von_Humboldt">Alexander-von-Humboldt</A> <A HREF="http://www.humboldt-foundation.de/web/home.html">foundation</A>. During this time I was a visitor in the group of -<A HREF="http://www.mathematik.uni-muenchen.de/~schwicht/">Prof. Helmut Schwichtenberg</A>. -Since 2006 this work is supported by an +<A HREF="http://www.mathematik.uni-muenchen.de/~schwicht/">Prof. Helmut Schwichtenberg</A> in Munich. +Between 2006 and 2011 this work is supported by an <A HREF="http://en.wikipedia.org/wiki/Emmy_Noether">Emmy-Noether</A> -<A HREF="https://www.dfg.de/en/research_funding/programmes/individual/emmy_noether/">fellowship</A>. +<A HREF="https://www.dfg.de/en/research_funding/programmes/individual/emmy_noether/">fellowship</A> at the TUM. There is a <A HREF="https://nms.kcl.ac.uk/christian.urban/Nominal/">webpage</A> about Nominal Isabelle, which also includes a list of projects that use Nominal Isabelle. Users of Nominal Isabelle had their papers appearing at LICS, POPL, FOSSACS, SOS, TPHOLs, CPP, SEFM, the Haskell Symposium and -in the Journal of Automated Reasoning. +in the Journal of Automated Reasoning. Nowadays, Nominal Isabelle 2 is part of the <A HREF="https://www.isa-afp.org">Archive of Formal Proofs</A>. +</TD> +</TR> + +<TR> +<TD BGCOLOR="#FFFFFF" WIDTH="75%"> +<B>Real-Time Scheduling and Priority Inheritance</B> + In real-time operating systems with processes, resource locking and + priority scheduling, one faces the problem of + <A HREF="http://en.wikipedia.org/wiki/Priority_inversion">priority inversion</A> (processes + with lower priority block processes with higher priority indefinitely). If you do not prevent this problem, + then processes can behave erratically, as <A HREF="http://www.nasa.gov">NASA</A> found out the + <A HREF="http://catless.ncl.ac.uk/Risks/19.54.html#subj6">hard</A> way with their first + <A HREF="http://www.nasa.gov/mission_pages/mars-pathfinder/index.html">Mars Pathfinder mission</A>. + The priority inheritance protocol is a widely used scheduling algorithm that prevents + priority inversion. However, the <A HREF="http://dx.doi.org/10.1109/12.57058">original paper</A> + describing this algorithm contains an incorrect algorithm and a bogus(!) correctness proof. + + We formalised our version of the priority inheritance protocol, including a generalisation + of the original work (we allow overlapping critical sections) in the theorem prover + <A HREF="http://isabelle.in.tum.de">Isabelle</A>. + + In our formalisation we use the inductive method we learned from + <A HREF="https://www.cl.cam.ac.uk/~lp15/">Prof. Larry Paulson</A>. + He used this method in order to prove the correctness of security + protocols. We have implemented our algorithm on top of the + the small <A HREF="https://en.wikipedia.org/wiki/Pintos">PINTOS</A> + operating system used for teaching (we passed all their test cases and were + faster than their reference implementation). + + + While the problem with the original algorithm was already known for some time, the incorrect + specification seems to be still widely in use and described in many textbooks on real-time operating systems, + including famous and rather expensive + ones. Feel free to decide whether they are worth your time and money. Task: Spot the problems in + <A href="https://www.amazon.com/Real-Time-Systems-Design-Analysis-Practitioner-ebook/dp/B0062LNOCW">here</A>, + <A href="https://www.amazon.co.uk/Real-Time-Concepts-Embedded-Systems-Qing/dp/1578201241">here</A>, + <A href="https://www.amazon.co.uk/Real-Time-Systems-Jane-W-Liu/dp/0130996513">here</A>, + <A href="https://www.springer.com/gp/book/9780792392118">here</A> and + <A href="https://www.os-book.com/OS9/">here</A>! + Alternatively, you can look at the quotes and pointers in our + <A HREF="http://nms.kcl.ac.uk/christian.urban/Publications/pip.pdf">paper</A>. A notable + exception is the <A HREF="https://www.springer.com/gp/book/9781461406754">textbook</A> + by Buttazzo, who gives the correct specification. Unfortunately, his work did not + help us with proving the correctness of the priority inheritance protocol. + + This is joint work with Prof. Xingyuan Zhang and his student Chunhan Wu from the + <A HREF="http://www.ust.com.cn/">PLA University of Science and Technology</A> in Nanjing. </TD> </TR> @@ -261,39 +308,6 @@ </TD> </TR> -<!-- -<TR> -<TD BGCOLOR="#FFFFFF" WIDTH="75%"> -<B>Priority Inheritance</B> - In real-time operating systems with processes, resource locking and - priority scheduling, one faces the problem of indefinite - <A HREF="http://en.wikipedia.org/wiki/Priority_inversion">priority inversion</A> (processes - with lower priority block processes with higher priority). If you do not prevent this problem, - then processes can behave quite erratically, as <A HREF="http://www.nasa.gov">NASA</A> found out the - <A HREF="http://catless.ncl.ac.uk/Risks/19.54.html#subj6">hard</A> way with their - <A HREF="http://www.nasa.gov/mission_pages/mars-pathfinder/index.html">Mars Pathfinder mission</A>. - The priority inheritance protocol is a widely used scheduling algorithm that prevents - priority inversion. However, the <A HREF="http://dx.doi.org/10.1109/12.57058">original paper</A> - describing this algorithm contains an incorrect algorithm and a bogus correctness proof - (this seems to be the only "proof" about priority inheritance in the literature). - - We formalised the priority inheritance protocol, including a generalisation - of the original work. - - using the inductive method we learned from - <A HREF="https://www.cl.cam.ac.uk/~lp15/">Prof. Larry Paulson</A>. - While the problem with the original algorithm was already known, the incorrect - specification seems to be still in use - - <A HREF="http://mcs.une.edu.au/%7Eiam/Data/threads/node15.html">here</A> - <A HREF="http://ems2.be/Portals/6/course_docs/OS_pathfinder_failure.ppt"> - - This is joint work with Prof. Xingyuan Zhang and his student Chunhan Wu from the - <A HREF="http://www.ust.com.cn/">PLA University of Science and Technology</A> in Nanjing. -</TD> -</TR> ---> - <TR> <TD BGCOLOR="#FFFFFF" WIDTH="75%"> <B>Nominal Unification and Alpha-Prolog</B> @@ -370,7 +384,7 @@ </TABLE> <P> -Time-stamp: <- 2017-09-26 19:52:51 by Christian Urban> <a href="https://validator.w3.org/check/referer">[Validate this page.]</a> +</font> </BODY> </HTML>