Database: scholar
Question: what topics does oren etzioni write about most ?
SQL:
SELECT DISTINCT COUNT ( t2.keyphraseid )  ,  t2.keyphraseid FROM paper AS t3 JOIN paperkeyphrase AS t2 ON t3.paperid  =  t2.paperid JOIN writes AS t4 ON t4.paperid  =  t3.paperid JOIN author AS t1 ON t4.authorid  =  t1.authorid WHERE t1.authorname  =  "oren etzioni" GROUP BY t2.keyphraseid ORDER BY COUNT ( t2.keyphraseid ) DESC;