The PhD thesis written by Ronald Fagin at the University of California, Berkeley, established a fundamental link between existential second-order logic and the complexity class NP. This proof, now known as Fagin's theorem, provided a bedrock for the development of finite model theory, shaping how researchers approach decision problems and non-deterministic Turing machines within computational complexity.
Academic Background
Born in 1945 in Oklahoma City, Fagin attended Northwest Classen High School before continuing his education at Dartmouth College. He completed his doctoral studies in 1973 under the supervision of Robert Vaught at the University of California, Berkeley. Shortly after graduation, he joined the IBM Research Division, beginning his tenure at the Thomas J. Watson Research Center.
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Fagin transferred to IBM Research – Silicon Valley in San Jose, California, in 1975. His work encompasses database theory and reasoning about knowledge. Beyond his theorem on NP complexity, he demonstrated that first-order logic possesses a zero-one law, indicating that the probability of a first-order sentence being satisfied by an n-node structure converges to zero or one as n approaches infinity. He also developed theoretical frameworks for higher normal forms in databases, specifically 4NF, 5NF, and DK/NF.
Algorithms and Recognition
The scientific community identifies several concepts through his name, including Fagin's algorithm for score aggregation and the Fagin-inverse used in data exchange. Throughout his career, he has served as committee chair for numerous professional gatherings, such as the ACM Symposium on Principles of Database Systems and the International Conference on Database Theory. His collaborative work includes the 1995 book Reasoning about Knowledge.
Honors and Affiliations
Fagin maintains memberships in the National Academy of Sciences, the National Academy of Engineering, the American Academy of Arts and Sciences, and the IEEE. His accolades include the 2014 Gödel Prize, the 2020 Alonzo Church Award, and the 2012 W. Wallace McDowell Award. He also received an honorary doctorate from Paris Dauphine University.
Fast facts
- Born: 1945, Oklahoma City
- Education: Dartmouth College, University of California, Berkeley
- Employer: IBM
- Key Theorem: Fagin's theorem
- Selected Award: Gödel Prize (2014)
- Professional Fellowship: ACM Fellow
- Notable Field: Finite model theory
Questions readers ask
What is Fagin's theorem?
It identifies that a decision problem is expressible in existential second-order logic if and only if it is solvable by a non-deterministic Turing machine in polynomial time.
Where did Fagin conduct his research?
He spent his career within the IBM Research Division, primarily at IBM Research – Silicon Valley.
Achievements
- Gödel Prize — 2014
- Held posts at IBM
- Fields: mathematics
