ALGORITHMIC ASPECTS OF FLOWS IN NETWORKS

fEt moi, . . . . sifavait sucommenten rcvenir, One service mathematics has rendered the jen’yseraispointall,,: human race. It hasput rommon senseback JulesVerne whereit belongs, on the topmost shelf next tothedustycanisterlabelled’discardednon­ Theseriesis divergent; thereforewemaybe sense’. ahletodosomethingwithit. EricT. Bell O. Heaviside Mathematicsisatoolforthought. Ahighlynecessarytoolinaworldwherebothfeedbackandnon­ linearitiesabound. Similarly, allkindsofpartsofmathematicsserveastoolsforotherpartsandfor othersciences. Applyinga simplerewritingrule to thequoteon theright aboveonefinds suchstatementsas: ’One service topology hasrenderedmathematicalphysics . . . ’; ’Oneservicelogichasrenderedcom­ puterscience . . . ’;’Oneservicecategorytheoryhasrenderedmathematics . . . ’. Allarguablytrue. And allstatementsobtainablethiswayformpartoftheraisond’etreofthisseries. This series, Mathematics and Its Applications, started in 1977. Now that over one hundred volumeshaveappeareditseemsopportunetoreexamineitsscope. AtthetimeIwrote Growing specialization and diversification have brought a host of monographs and textbooks on increasingly specialized topics. However, the ’tree’ of knowledge of mathematics and related fields does not grow only by puttingforth new branches. It also happens, quiteoften in fact, that branches which were thought to becompletely disparatearesuddenly seento berelated. Further, thekindandlevelofsophistication of mathematics applied in various sciences has changed drastically in recent years: measure theory is used (non-trivially)in regionaland theoretical economics; algebraic geometryinteractswithphysics; theMinkowskylemma,codingtheoryandthestructure of water meet one another in packing and covering theory; quantum fields, crystal defectsand mathematicalprogrammingprofit from homotopy theory; Liealgebras are relevanttofiltering; andpredictionandelectricalengineeringcanuseSteinspaces. And in addition to this there are such new emerging subdisciplines as ’experimental mathematics’,’CFD’, ’completelyintegrablesystems’,’chaos, synergeticsandlarge-scale order’, whicharealmostimpossibletofitintotheexistingclassificationschemes. They drawuponwidelydifferentsectionsofmathematics. By andlarge, all this stillapplies today. Itis still truethatatfirst sightmathematicsseemsrather fragmented and that to find, see, and exploit the deeper underlying interrelations more effort is neededandsoarebooks thatcanhelp mathematiciansand scientistsdoso. Accordingly MIA will continuetotry tomakesuchbooksavailable. If anything, the description I gave in 1977 is now an understatement.