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Alberto Mendelzon at Princeton: The Blossoming of Relational Database Theory David Maier Dept. of Computer Science Portland State University DB Theory: Toronto to Princeton • Dennis Tsichritzis (Toronto) goes to IBM Yorktown Heights for the summer to work on OS. Finds database work with Frank King, Don Chamberlin and Ray Boyce more interesting (1973). • Returns to Toronto, announces to OS group (including Phil Bernstein) that they are now the DB group. • Phil does PhD on 3NF synthesis (1975), remains at UT as a postdoc. • Catriel Beeri arrives at Toronto for a postdoc (75-76), shares an office with Phil. Switches from automata to database theory. The Word Spreads • Phil goes to Harvard (1976) • Catriel goes to Princeton (1976), teaches DB class, gets Ullman and Aho interested in relational databases • Most of Ullman’s PhD students start working on relational database theory Alberto arrives in Fall 1975, becomes one of the first of Ullman’s students working on database theory Main Questions • Dependency implication + What kind of dependencies are there? • What’s a good DB scheme? + What’s a good a good class of DB schemes? • When are two DB schemes equivalent? + What does “equivalent” mean? • When are two queries equivalent? Realizations • 23 • Not every dependency is an FD • Real DBs aren’t always the projection of a single instance First Papers J. Howard MY AVA RF CB YS JDU PAB N. Goodman 1977 1978 We Get Hyper ES R.E.Ladner PH MY AVA RF YS DM CB MYV JDU AOM PAB FS HFK 1977 1978 1979 1980 CHP 1979-80 Work • MVDS: Independence of inference axioms • Chase: Tableaux as mappings, tableaux as templates [MMS] • Equivalence: Same set of fixpoint instances (vs. embedding equivalent FDs) [BMSU] • Adequacy of decompositions: Distinguishing Rissanen’s, Arora & Carlson’s notions [MMSU] • Generalized mutual dependencies [MM] Are We Cyclic Yet? C.Delobel ES PH CHP D.S.Parker MY AVA RF YS DM CB MYV JDU AOM PAB FS HFK 1977 1978 1979 1980 1981 DSW 1981-2 Topics • Acyclic database schemes: 9 characterizations end up being equivalent; JD = MVDs [BFMMUY] • Weak instance model, testing equivalence w/ tableaux • Equivalence of queries with dependencies [GM] Need to Stop Somewhere ES PH CHP M.Casanova S.Walecka S.Kuck MY AVA YS RF DM CB MYV JDU AOM PAB FS HFK 1977 1978 1979 1980 1981 1982 DSW M.Graham J.Stein D.Rozenshtein S.Salveter 1983 & Beyond Publishing with students at Toronto Graphical query languages Deductive databases
