Leading a Double LifeOctober 21, 2000
Mario Primicerio, having started his scientific life as a physicist, soon turned his attention to applied mathematics and, in particular, to free boundary problems. A free boundary, whose location is unknown in advance, separates two physical regimes, such as water and ice in the famous Stefan heat conduction problem. Free boundaries, whether static or moving, occur in a variety of settings, such as phase transitions, flow in porous media, shock waves in gas dynamics, propagating cracks, and reaction-diffusion systems. They come up in optimal control and, in recent years, in the unexpected context of financial mathematics: The value of an American option is calculated by solving a free boundary problem!
Primicerio's contributions to the field are pervasive, but two stand out: (a) development of the concept of a "mushy region" where the sharp boundary between two phases is replaced by a region where they are mixed, and (b) investigation of the relationship between classical and weak solutions.
As one of the founders of ECMI (the European Consortium for Mathematics in Industry) and of SIMAI (Societa Italiana di Matematica Applicata e Industriale), he has had a leading role in industrial mathematics. He has directed research projects in industrial mathematics with such impressive titles as coal-water suspension, ground freezing, crude oil extraction, and polymerization. But my favorites are those dealing with mathematical models for the percolation of water through ground coffee beans and with optimal grain-size distribution for the preparation of espresso. That should enable Italy to repel the impending Starbucks invasion!
Primicerio has been a full professor at the University of Florence since 1975, and has also served as dean of the Faculty of Sciences and as chairman of the Graduate Program in Mathematics. He has of course served on more than his share of committees and editorial boards, but it is worth mentioning that since his return to the university in 1999, he has been very active with the new journal Interfaces and Free Boundaries.
In recognition of his scientific achievements, Primicerio was elected to the celebrated Italian Academy, the Acca-demia Nazionale dei Lincei.
I.S.: As mayor of Florence, you had major responsibility for the well-being of half a million people, but you were also the guardian of some of the world's greatest Gothic and Renaissance art treasures. How were you able to balance these responsibilities?
M.P.: The two responsibilities are much closer and similar to each other than they appear. An art city should not become a museum, a dead city. On the contrary, it should remain a community to which one is proud to belong, a place where living is reasonably easy and where investments can be rewarding: In other words, art treasures can be an asset not only in terms of tourist attractions, but also in more general economic and quality-of-life terms. For these reasons, I consider that starting a large program of investments in infrastructure (e.g., a new underground railway and station, tramways, a new courthouse, highways) is part of a "philosophy" of interventions more directly related to culture and art (e.g., renovation and reopening of a 17th-century theatre, the "Uffizi project," creation of a Center for Contemporary Art, renovation and reuse of historical buildings and monasteries) and to the promotion of the city as the ideal venue for international meetings and conferences (European Summit, Bosnia mid-term conference, World Heritage Congress, etc.).
I.S.: Please comment further on what you see as the most significant achievements of your administration.
M.P.: At the end of my term in office, the administration published a two-column booklet listing our proposed programs in the first column and what was or was not done about them in the second column. I mention this only to show the spirit of openness of our administration---which was seen as a welcome change from traditional city government politics. Passing to what was done, I must explain that many of our cities had long stagnated as indecisive administrations failed to act so as to avoid problems and responsibilities. This was particularly true for Florence, most of whose wealthy people live on income from capital rather than from current production activities. We tried to introduce a sharp discontinuity (at least in the first derivative!) by initiating a vast program of public and private investment. As already mentioned, we took some difficult but relevant decisions in the area of transportation infrastructure; we also introduced important innovations in the fields of social services and housing-more than 1000 apartments built or totally renovated is a large number for a relatively small city---and in the tax system, where evasion of local taxes has been virtually eliminated, enabling us to maintain taxes at a constant level over four years even though the national contribution of funds to the city was cut by around 25%.
As mayor of Florence, Mario Primicerio set aside his research on free boundary problems to pursue solutions of a distinctly different nature: renovating a 17th-century theatre, creating a contemporary art center, starting a large program of investments in infrastructure. . . .
I.S.: How did you get into politics in the first place?
M.P.: Actually, I have been interested in politics for a long time, but until recently I was not directly involved in government or in any party. Five years ago, Italy was living in an unusual period: Traditional parties were no longer trusted, hope of a new spirit was emerging, and some nonprofessional politicians (professors, businessmen, engineers, bankers, . . .) were chosen as candidates. So was I!
I.S.: You are being too modest. By 1994, you had already earned the respect of your compatriots for your pro bono activities to improve social conditions and to mediate international conflicts. I recall your early efforts to bring together Arabs and Israelis in informal meetings to reduce tensions. Also, in the mid-sixties, you were a member of a delegation that met with the leaders of North and South Vietnam to try to end the war between them. But let us turn to the election process in Italy, which is probably different from the system in the U.S. When you ran for mayor, which party did you represent?
M.P.: In our system, mayors are elected directly by the citizens. To be elected, a candidate has to receive a majority of the votes cast; if no one achieves this on the first ballot (when several candidates are usually present), there is a runoff between the two top vote getters. At the same time, the City Council is elected, and the coalition supporting the winner gets a "bonus" to ensure that the majority has 60% of the seats on the Council. Before the campaign starts, the parties of the coalition must accept and sign the program presented by the candidate they support. The coalition supporting me was a center-left coalition that also supported Prime Minister Prodi at the national level. We won with 59% of the votes on the first ballot.
I.S.: Were there occasions when mathematics was useful to you during your term in office?
M.P.: In general, scientific mentality and method were very useful in dealing with administrative problems. In a few special cases I used mathematical formulas: for instance, to express the cost-sharing of services in terms of the revenue, or as a shortcut to evaluate the best offer in the financial market. Moreover, I stressed the introduction of computers, use of e-mail, creation of an official Web site, etc.; but this is not mathematics, it is everyday life!
I.S.: I seem to remember there was once a serious flood when the Arno overran its banks. Was that a concern during your term?
M.P.: In our complicated administrative system, responsibility for the main rivers belongs to the national government. But, of course, a mayor cannot confine his actions to the organization of emergency services! After a long and exhausting debate, our general plan for the safety of the Arno basin was approved by the Parliament. The next crucial step will be the implementation of the plan, which already has been partially financed.
I.S.: I am sure you must have attended Italian and international conferences of elected officials. Any interesting anecdotes? How did your colleagues react when they learned that you are a mathematician and a physicist?
M.P.: In addition to the meetings of the Italian conference of mayors, we had regular meetings of the mayors of the 12 major cities. I was also invited to attend the U.S. conference of mayors and to speak on the economic relevance and social benefits of the promotion of culture in a city (and then everybody thought I was an art historian); but when the mayors of the largest European cities met to discuss the problems of air pollution, I was asked by my colleagues to "translate" the talks given by technical experts into a more understandable language (". . . since you were a scientist . . . ," but I didn't like the past tense they used!).
I.S.: My usually reliable sources in Florence told me you probably would have been reelected, had you chosen to run again. Why did you decide not to?
M.P.: Your sources were quite right, but this was my last chance to return to science! As a matter of fact, after five more years away from mathematics it would have been impossible to recapture the pace of research. Moreover, the stress of the life of a mayor (who has to face many responsibilities with enormous external restrictions on his decision powers) is such that, without a long period of training for it, there is a real threat to one's psychophysical equilibrium. Finally, I believe in the proverb "Every season has its fruit."
As the idea for this interview was taking shape, Ivar Stakgold came across a short story in The New Yorker by another acquaintance, Manil Suri, who responded to congratulations with the news that he was about to become a published novelist. A theme seemed to be emerging-mathematical scientists who have succeeded in other, unexpected arenas, completely separate from mathematics.