Acknowledgments
This book is dedicated to Philippe Flajolet, the father of analytic combinatorics, our
friend andmentorwho passed away suddenly on March 22, 2011.An obituary – from
which we freely borrow here – was recently published by Salvy, Sedgewick, Soria,
Szpankowski,andVallee(2011).
WebelievethatthisbookwaspossiblethankstothetirelesseffortsofPhilippeFlajolet,
hisextensiveandfar-reachingbodyofwork,andhisscientificapproachtothestudyof
algorithms, including the development of the requisite mathematical and computational
tools.Philippeisbestknownforhisfundamentaladvancesinmathematicalmethodsfor
the analysis of algorithms; his research also opened new avenues in various areas of
applied computer science, including streaming algorithms, communication protocols,
databaseaccessmethods,datamining,symbolicmanipulation,text-processingalgorithms,
and random generation. He exulted in sharing his passion: his papers had more than a
hundreddifferentco-authors(includingthepresentauthors)andhewasaregularpresence
atscientificmeetingsallovertheworld.
PhilippeFlajolet’sresearchlaidthefoundationofasubfieldofmathematicsnowknown
as analytic combinatorics. His lifework Analytic Combinatorics (Cambridge University
Press, 2009, co-authored with R. Sedgewick) is a prodigious achievement, which now
defines the field and is already recognized as an authoritative reference. Analytic
combinatorics is a modern basis for the quantitative study of combinatorial structures
(suchaswords,trees,mappings,andgraphs),withapplicationstoprobabilisticstudyof
algorithmsbasedonthesestructures.Italsostronglyinfluencesotherscientificareas,such
asstatisticalphysics,computationalbiology,andinformationtheory.Withdeephistoric
rootsinclassicalanalysis,thebasisofthefieldliesintheworkofKnuth,whoputthe
studyofalgorithmsontoafirmscientificbasis,startinginthelate1960swithhisclassic
series of books. Philippe Flajolet’s work took the field forward by introducing original
approachesintocombinatoricsbasedontwotypesofmethods:symbolicandanalytic.The
symbolic side is based on the automation of decision procedures in combinatorial
enumerationtoderivecharacterizationsofgeneratingfunctions.Theanalytic sidetreats
those generating functions as functions in the complex plane and leads to a precise
characterizationoflimitdistributions.
Finally, Philippe Flajolet was the leading figure in the development of a large
internationalcommunity(whichagainincludesthepresentauthors)devotedtoresearchon
probabilistic, combinatorial, and asymptotic methods in the analysis of algorithms. His
legacyisalivethroughthiscommunity.Wearestilltryingtocopewiththelossofour
friendandmentor.
Whileputtingthefinaltouchestothisbook,thetragicshootingoccurredinParisofthe
famous French cartoonists at Charlie Hebdo. We are sure that this event would shock
Philippe Flajolet, who had an inimitable sense of humour. He mocked himself and his
friends.Wewereoftenonthereceivingendofhishumour.Wetookit,asmostdid,asa
proofofaffection.Cartoonistsand scientistshavesomething incommon: offendingthe