Table schema:
CREATE TABLE authorship (authid VARCHAR, paperid VARCHAR); CREATE TABLE authors (lname VARCHAR, fname VARCHAR, authid VARCHAR); CREATE TABLE papers (paperid VARCHAR)

Question: What is the last name of the author that has published the most papers?
SQL: SELECT t1.lname FROM authors AS t1 JOIN authorship AS t2 ON t1.authid = t2.authid JOIN papers AS t3 ON t2.paperid = t3.paperid GROUP BY t1.fname, t1.lname ORDER BY COUNT(*) DESC LIMIT 1