Loop invariants: the musical






  Actually it is not a musical but an extensive survey. I have long been fascinated by the notion of loop invariant, which describes the essence of a loop. Considering a loop without its invariant is like conducting an orchestra without a score. In this submitted survey paper written with Sergey Velder and Carlo Furia … Read more




Computer scientist gallery, updated






After several months of inaction I have updated my “Gallery of Computer Scientists” [1]. It benefits from many recent meetings where the density per square meter of Turing award winners and other brilliant computer scientists was hard to beat, most notably the two extraordinary Turing centenary celebrations  — the ACM event in San Francisco, and … Read more




Technology plus






As the name indicates, this blog is particularly devoted to technology, and even more particularly to software technology. My technical persona is not, however, completely cut off from my personal persona and I increasingly include non-software topics. Whether there is any readership equally interested in learning about using domain theory for specification and finding out … Read more




Handshake with a clown






In the circus business, the Zavatta family is a legend. From father to son and grandson, a Zavatta has for decades been the foremost clown of his generation, first in Italy, then in French North Africa, then in France proper. None was ever more famous than Achille Zavatta, who carried the family name through the … Read more




Word of the day






Word Umlottery [ˈʊm.lɑːɾɚɹi] (fr. umloterie, f; ger. Umlotterie, f.; it. umlotteria, f.; rus. умлотерия , f.). Definition A spur-of-the-moment and generally random decision, by a hesitant speaker of German talking in front of a (typically large) native-speaker audience, to pronounce the next intended word with, or without, an umlaut on the decisive syllable. Example use … Read more




A fundamental duality of software engineering






A couple of weeks ago I proposed a small quiz. (I also stated that the answer would come “on Wednesday” — please understand any such promise as “whenever I find the time”. Sorry.) Here is the answer. The quiz was: I have a function: For 0 it yields 0. For 1 it yields 1. For … Read more