Johan Torkel Håstad (Swedish pronunciation: ; born 19 November 1960) is a Swedish theoretical computer scientist most known for his work on computational complexity theory. He was the recipient of the Gödel Prize in 1994 and 2011 and the ACM Doctoral Dissertation Award in 1986, among other prizes. He has been a professor in theoretical computer science at KTH Royal Institute of Technology in Stockholm, Sweden since 1988, becoming a full professor in 1992. He is a member of the Royal Swedish Academy of Sciences since 2001. He received his B.S. in Mathematics at Stockholm University in 1981, his M.S. in Mathematics at Uppsala University in 1984 and his Ph.D. in Mathematics from MIT in 1986. Håstad's thesis and 1994 Gödel Prize concerned his work on lower bounds on the size of constant-depth Boolean circuits for the parity function. After Andrew Yao proved that such circuits require exponential size, Håstad proved nearly optimal lower bounds on the necessary size through his switching lem