user: Question: In which district is Robert W. Edgar the incumbent?
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result', 'Candidates']
Types: ['text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['Pennsylvania 4', 'Joseph P. Kolter', 'Democratic', 1982.0, 'Re-elected', 'Joseph P. Kolter (D) 56.8% Jim Kunder (R) 43.2%']
SQL:

assistant: SELECT "District" FROM "Table" WHERE "Incumbent" = 'Robert W. Edgar';