diff -r e53441994412 -r 99f91bb99418 lex/index.html --- a/lex/index.html Wed May 18 11:50:59 2016 +0100 +++ b/lex/index.html Wed May 18 13:45:30 2016 +0100 @@ -33,7 +33,7 @@ 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 +``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 @@ -44,27 +44,27 @@ 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. +explain why the gaps in this argument cannot be filled easily. +

Theory Files for Isabelle 2016

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