In 2011, shortly after his untimely passing, several colleagues and I wrote an obituary for Philippe Flajolet  that includes the following:
He was the leading figure in the development of the international ‘AofA’ community that is devoted to research on probabilistic, combinatorial, and asymptotic methods in the analysis of algorithms. The colleagues and students who are devoted to carrying on his work form the core of his primary legacy.
This special issue is testimony to that legacy. Many of the dozens of authors who are represented here worked closely with Philippe; many others have been inspired by his work. All are devoted to carrying it on.