squares that cannot be possibly covered by own pawns, usually also controlled by the enemy pawns. A typical example is d4 square after White forms a triangle consisting of pawns on c4, d3 and e4. Holes are excellent locations for enemy minor pieces, safer than outposts. For that reason one should keep minor pieces to cover the holes in one's position. Along with bitboard pawn patterns, holes may be determined by the relative complement of front attack spans usually restricted to the area of the own 3rd and 4th rank of the extended center.
Hole on d4
- Pawn Structure "Holes" and Move Ordering by Daniel A. Thies in rgcc February 12, 1996 » Move Ordering
- Re: Did Cray Blitz really have a win? by Robert Hyatt, rec.games.chess.misc, March 12, 1999 » ACM 1985, WCCC 1986, Cray Blitz
- Hole | Glossary of chess from Wikipedia
- The Sicilian – Boleslavsky hole | Pawn structure from Wikipedia
- Simulated view of a black hole (center) in front of the Large Magellanic Cloud. Note the gravitational lensing effect, which produces two enlarged but highly distorted views of the Cloud. Across the top, the Milky Way disk appears distorted into an arc. Image by Alain r, September 08, 2006 CC BY-SA 2.5, Wikimedia Commons