I've reached another milestone of sorts. Even though I still haven't located 7 of the edge pieces I'm declaring victory and moving on. It's now pretty clear that the puzzle will cover all but the very edge of the white table. Which if you haven't guessed is a door. The question of whether there really are 4000 pieces came up. The puzzle is organized in rows and columns, 40 rows, 100 columns, 4000 pieces. Now as to whether all 4000 pieces are there, time will tell. My approach from here is to work on the easiest parts first and gradually progress to more difficult parts. If my logic is correct, this should make the more difficult parts easier since there will be fewer unplaced pieces when I get there.