This book is a selection of my published and unpublished papers written between 1968, when I came to the United States, and 2014. The ideas for them came to me at different times and in different circumstances. I have worked as a theoretical mathematician in the Czech Academy of Sciences, as a vice-president in a large U.S. bank, as an external consultant in a small investment technology software developer, as a full-time professor and a visiting professor at several universities. I have been a founding partner and a managing director in a startup, a special adviser for a large bond rating firm and, since 2010, an independent researcher not associated with any institution.

I cannot say which was the most satisfying. It has all been fun, and still is. I have met, and in many cases worked with, many extremely interesting and capable people. These meetings, discussions, and collaboration have meant a lot to me.

I have usually worked somewhat outside the organizational structure. I have never had a subordinate, which was exactly as I wanted it. And I have been very fortunate that I rarely found much discrepancy between what I wanted to work on, and between what seemed to be needed at the time.

I have enjoyed collaborating with other people. A number of the papers in this collection are joint works. I would like to take this opportunity to thank my coauthors: Gifford Fong, my one-time employer and long-time friend, with whom I wrote six of the papers here; John McQuown, who hired me to Wells Fargo Bank on my arrival to the USA, with whom, along with Stephen Kealhofer, we founded the KMV Corporation years later, and with whom I have been friends the whole time; my colleague at the University of Rochester, the late Professor Julian Keilson; and the tireless and resourceful Professor Helyette Geman, who arranged my pleasant stay at ESSEC. I appreciate their input, insights, and joint work.

I would like to express my thanks and appreciation to many people. There are some, however, that I cannot but mention specifically: my father, JUDr. Oldřich Vašíček, who encouraged and supported my interest in mathematics from early childhood; the late Professor Alois Apfelbeck, much feared for his first-year analysis class, who singlehandedly, and successfully, opposed the Party authorities from expelling me from the university; John McQuown, who introduced me to finance; Professor Richard Roll, whose critique of an earlier draft of my 1977 paper made me to rewrite it for much improvement; and Professor Robert Merton, one of the smartest yet gracious people I know. To these and many other people who helped me by advice, debate, collaboration, or example, I wish to give my gratitude.

Oldrich Alfons Vasicek
August 2014