By Shin | Published: May 6, 2010
In the recent work of Sharon and me on maximally dense segments we needed quite a number of functions to be monotonic, idempotent, etc. It only occurred to me after submitting the paper: could they be defined as Galois connections?
By Shin | Published: April 5, 2010
Sharon and I have finally concluded, for now, our work on the maximally dense segment problem (download the draft here), on which we have been working on and off for the past two years. Considering the algorithm itself and its derivation/proofs, I am quite happy with what we have achieved. The algorithm is rather complex, however, and it is a challenge presenting it in an accessible way. Sharon has done a great job polishing the paper, and I do hope more people would be interested in reading it and it would, eventually, inspire more work on interesting program derivations.
By Shin | Published: April 5, 2010
Sharon Curtis and Shin-Cheng Mu. Functional pearl: maximally dense segments. Submitted.
[PDF]
By Shin | Published: April 5, 2010
In a previous paper of mine, regrettably, I wrongly attributed the origin of the maximum segment sum problem to Dijkstra and Feijen’s Een methode van programmeren. In fact, the story behind the problem was told very well in Jon Bentley’s Programming Pearls.
I learned the function derivation of the maximum segment sum problem from one of Jeremy’s papers and was very amazed. It was perhaps one of the early incident that inspired my interest in program calculation.
By Shin | Published: April 3, 2010
Code and proof accompanying our forthcoming paper Functional Pearl: Maximally Dense Segments.
By Shin | Published: June 20, 2009
Reviewing Zantema’s “windowing” technique for computing the longest segment of the input that satisfies a suffix-closed predicate.
By Shin | Published: June 7, 2009
Translating Zantema’s work to Bird-Meertens style, to compute the longest consecutive segment of the input that satisfies a predicate that is suffix and overlap-closed.
By Shin | Published: June 2, 2009
Giving a constructive proof for one of the essential properties in Hans Zantema’s Longest Segment Problems.
By Shin | Published: November 13, 2007
S-C. Mu. Maximum segment sum is back: deriving algorithms for two segment problems with bounded lengths. In Partial Evaluation and Program Manipulation (PEPM ’08), pp 31-39. January 2008.
[PDF] [GZipped Postscript]
By Shin | Published: November 11, 2007
To practise using the Logic.ChainReasoning module in Agda, Josh proved the foldr-fusion theorem, and I thought it would be an small exercise over the weekend to start off where he finished…