1. EUFSLAT award to Petr Ha’jek It is a pleasure for me to be here and to have the possibility to say some words about Petr Ha’jek. For me and for many other people, he is not only a great scientist, but also a teacher and a friend. Each of us could tell a lot of stories about Petr motivating his great personality. But at this moment we are celebrating him as a scientist, and hence we will mainly speak about his scientific activity.

2. Petr’s scientific activity Before speaking about fuzzy logic, which in the last two decades has become Petr’s main research field, let me recall that his activity is by no means limited to fuzzy logic. Petr wrote an important book with Vopenka about the theory of semisets. Then he greatly contributed to the metamathematics of arithmetic and wrote another important book with Pudlak.

3. Petr’s scientific activity At the same time, he did a great work about the applications (see the GUHA method). Petr’s work on Fuzzy Logic is a good compromise between mathematical abstract theory and applications. In his book Metamathematics of Fuzzy Logic, Petr takes into account both aspects: he provides for a mathematical apparatus for fuzzy logic, thus considering problems like completeness, standard completeness, decidability, Co-NP completeness etc.

4. Petr’s work on Fuzzy Logic Moreover he invented an important new fuzzy logic, namely, BL, which will probably be called H (Ha’jek’s logic); moreover he prepared the ground for the birth of other even weaker logics (the so called flea logics). But at the same time he does not study fuzzy logic in itself, but he is interested in its applications. For instance, logics with constants for truth degrees, fuzzy logics of probability, of possibility and of belief, fuzzy modal logics, fuzzy description logics.

5. The reasons for Petr’s success Petr Ha’jek is certainly a bright sceintist, but he is not the only good scientist in Logic or in Mathematics. So, we may ask: what are the reasons for his success? (Remember for instance that his book has a lot of citations). I think that a peculiarity of Petr is his ability to attract both abstract mathematicians and applied scientists. Abstract mathematicians are not enthousiastic about applications when such applications do not involve enough mathematics.

6. The reasons for Petr’s success On the other hand, applied researcher are skeptical about abstract results when do not see applications. Well, Petr showed that even applications may have an interesting mathematical theory, and hence may be attractive also for a pure mathematician. At the same time mathematics may be very useful in the applications, and hence it may attract applied researchers.

7. Conclusions Summing-up, I completely agree with the choice of Petr Ha’jek for the EUFSLAT award. Let me add that we are preparing a volume for Trends in Logic, outstanding contributions, which will be devoted to Petr Hàjek and his contribution to Mathematical Fuzzy Logic (a new research field, of which Petr is probably the leader). The volume is taking long, mostly due to my inefficiency, but I now think that we are close to the end. The goal of the volume is to show to the mathematical community that Petr’s work will be continued.

8. Conclusions But of course, the real conclusion is: THANK YOU, Petr, for your work, and congratulations for the EUFSLAT award.