passed away on Monday from a heart attack at the age of 73. I met Freivalds several times often through Carl Smith, who passed away himself in 2004. Rūsiņš, Carl, Bill, myself and a couple of others have a joint paper on inductive inference and measure theory. Freivalds is the sixth co-author I've lost and it never gets easier.
Rūsiņš Freivalds did much of the early work in probabilistic algorithms and automata, and in inductive inference, a computability-theoretic approach to learning. In the 70's he found fast probabilistic algorithms for checking multiplication of integers and matrices. More recently he has looked at quantum finite automata. He supervised several PhD students including Andris Ambainis, one of the leading researchers in quantum algorithms.
Mostly I remember Freivalds as the leader of the Latvian theoretical computer science community and just an extremely nice and friendly colleague. I am glad to have known and worked with him.