Patrick C. Fischer | Computer scientist, 75

Patrick C. Fischer, 75, a computer scientist whose theoretical work helped make Internet searches possible but who was most widely known as an early target of the so-called Unabomber, died Aug. 26 of stomach cancer in Montgomery County, Md.

Mr. Fischer was a professor of computer science at Vanderbilt University in Nashville when a pipe bomb concealed in a package addressed to him exploded in his office May 5, 1982, while lecturing in Puerto Rico. The package was opened by his secretary, who suffered cuts and burns. She returned to work three weeks later.

Investigators said he was apparently the fifth person targeted by the mail bomber, identified in 1996 after his arrest as Theodore Kaczynski, a Harvard-trained mathematician. Mr. Fischer later described scouring his memory for any possible links he might have had with Kaczynski in the late 1950s and early '60s at Cambridge, Mass. But while they knew many of the same people, he could not remember having met Kaczynski.

After teaching at Harvard, Cornell, and Pennsylvania State University, he was appointed chairman of the computer science department at Vanderbilt in 1980. (The package of explosives was initially sent to his office at Penn State before being forwarded to Vanderbilt.) He served as chairman of computer science there until 1995 and retired in 1998.

He was among an early group of mathematicians working in the field of database theory, founded on the work of Edgar F. Codd, an IBM scientist considered the inventor of database management. Mr. Fischer's study of the mathematics of query languages - the mechanics of database searches - was crucial in developing the systems now commonly employed by Google, Amazon, and other search sites.

- N.Y. Times News Service