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

Question: Find the number of papers published by the institution "University of Pennsylvania".
SQL: SELECT COUNT(DISTINCT t1.title) FROM papers AS t1 JOIN authorship AS t2 ON t1.paperid = t2.paperid JOIN inst AS t3 ON t2.instid = t3.instid WHERE t3.name = "University of Pennsylvania"