What are the paper IDs of papers presented in conferences has a homepage starts with "http://www.informatik.uni-trier.de/~ley/db/conf/"?
homepage starts with "http://www.informatik.uni-trier.de/~ley/db/conf/" refers to HomePage LIKE '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/%'
database name:db_id authors
Author table Author Cols: Id dtype integer, Name dtype text, Affiliation dtype text, 
Conference table Conference Cols: Id dtype integer, ShortName dtype text, FullName dtype text, HomePage dtype text, 
Journal table Journal Cols: Id dtype integer, ShortName dtype text, FullName dtype text, HomePage dtype text, 
Paper table Paper Cols: Id dtype integer, Title dtype text, Year dtype integer, ConferenceId dtype integer, JournalId dtype integer, Keyword dtype text, 
PaperAuthor table PaperAuthor Cols: PaperId dtype integer, AuthorId dtype integer, Name dtype text, Affiliation dtype text, 
