-- Database schema
| Author : Id [ INTEGER ] primary_key , Name [ TEXT ] , Affiliation [ TEXT ] | Conference : Id [ INTEGER ] primary_key , ShortName [ TEXT ] , FullName [ TEXT ] , HomePage [ TEXT ] | Journal : Id [ INTEGER ] primary_key , ShortName [ TEXT ] , FullName [ TEXT ] , HomePage [ TEXT ] | Paper : Id [ INTEGER ] primary_key , Title [ TEXT ] , Year [ INTEGER ] , ConferenceId [ INTEGER ] Paper.ConferenceId = Conference.Id , JournalId [ INTEGER ] Paper.JournalId = Journal.Id , Keyword [ TEXT ] | PaperAuthor : PaperId [ INTEGER ] PaperAuthor.PaperId = Paper.Id , AuthorId [ INTEGER ] PaperAuthor.AuthorId = Author.Id , Name [ TEXT ] , Affiliation [ TEXT ] |
-- -- What are the paper IDs of papers presented in conferences has a homepage starts with "http://www.informatik.uni-trier.de/~ley/db/conf/"?

SELECT T1.Id FROM Paper AS T1 INNER JOIN Conference AS T2 ON T1.ConferenceId = T2.Id WHERE T2.HomePage LIKE 'http://www.informatik.uni-trier.de/~ley/db/conf/%';