# HG changeset patch # User Christian Urban # Date 1457700483 0 # Node ID 880e62843614b81fc4a652dfde487075bf6ae746 # Parent ff462cfb41cbbe89c2383880049aba05f4f3efcc updated diff -r ff462cfb41cb -r 880e62843614 PhD/index.html --- a/PhD/index.html Mon Feb 15 23:28:10 2016 +0100 +++ b/PhD/index.html Fri Mar 11 12:48:03 2016 +0000 @@ -2,7 +2,7 @@ "http://www.w3.org/TR/REC-html40/loose.dtd"> Homepage of Christian Urban - + Links
-Home
-Publications
-Recent Talks +Home
+Publications
+Recent Talks

Handy Information
-People in Logic
-Programming Languages
-Miscellaneous +People in Logic
+Programming Languages
+Miscellaneous

@@ -47,7 +47,7 @@ Postscript file of the thesis: -ps.gz +ps.gz @@ -55,22 +55,22 @@

The Dinner after the Viva

organised by Gavin in The Three Horseshoes in Maddingley. Very nice.

-
+
My examiners, Andy Pitts and Henk Barendregt, are next to me. Nick Benton, Mrs. Barendregt-Kessing (Henk's mother), -Gavin Bierman, -Mateja Jamnik, +Gavin Bierman, +Mateja Jamnik, Martin Hyland and Glynn Winskel are standing behind.

-
+
There are Susan Pitts and Alice Benton on the left.

The Ceremony

-

+

diff -r ff462cfb41cb -r 880e62843614 lex/index.html --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/lex/index.html Fri Mar 11 12:48:03 2016 +0000 @@ -0,0 +1,68 @@ + + +HGMP + + + + + + + + + +
+

POSIX Lexing with Derivatives of Regular Expressions (Proof Pearl)

+ +Fahad Ausaf, Roy Dyckhoff, Christian Urban +

+ +Brzozowski introduced the notion of derivatives for regular +expressions. They can be used for a very simple regular expression +matching algorithm. Sulzmann and Lu cleverly extended this algorithm +in order to deal with POSIX matching, which is the underlying +disambiguation strategy for regular expressions needed in lexers. +Sulzmann and Lu have made available on-line what they call a +``rigorous proof'' of the correctness of their algorithm w.r.t. their +specification; regrettably, it appears to us to have unfillable gaps. +In the first part of this paper we give our inductive definition of +what a POSIX value is and show (i) that such a value is unique (for +given regular expression and string being matched) and (ii) that +Sulzmann and Lu's algorithm always generates such a value (provided +that the regular expression matches the string). We also prove the +correctness of an optimised version of the POSIX matching +algorithm. Our definitions and proof are much simpler than those by +Sulzmann and Lu and can be easily formalised in Isabelle/HOL. In the +second part we analyse the correctness argument by Sulzmann and Lu and +explain why it seems hard to turn it into a proof rigorous enough to +be accepted by a system such as Isabelle/HOL. + +

Theory Files for Isabelle 2016

+ +
+

+ Last modified: Fri Mar 11 12:20:03 GMT 2016 +[Validate this page.] + + diff -r ff462cfb41cb -r 880e62843614 logic.html --- a/logic.html Mon Feb 15 23:28:10 2016 +0100 +++ b/logic.html Fri Mar 11 12:48:03 2016 +0000 @@ -80,7 +80,7 @@

David Pym
Edmund Robinson
Frank Pfenning
-
Gavin Bierman
+
Gavin Bierman
George Necula
Gianluigi Bellin
Gilles Dowek
@@ -161,7 +161,7 @@

- Last modified: Fri Sep 27 13:02:45 BST 2013 + Last modified: Fri Mar 11 12:13:02 GMT 2016 [Validate this page.]