Table schema:
CREATE TABLE inst (country VARCHAR, instid VARCHAR); CREATE TABLE authorship (instid VARCHAR, paperid VARCHAR); CREATE TABLE papers (paperid VARCHAR)

Question: Retrieve the country that has published the most papers.
SQL: SELECT t1.country FROM inst AS t1 JOIN authorship AS t2 ON t1.instid = t2.instid JOIN papers AS t3 ON t2.paperid = t3.paperid GROUP BY t1.country ORDER BY COUNT(*) DESC LIMIT 1