What Are Endgame Tablebases (EGTB)?

Understanding Endgame Tablebases (EGTB) and Their Use in Chess

In chess, the endgame is a critical phase where precise play becomes even more important due to the reduced number of pieces on the board. To help players and engines calculate the optimal moves in these positions, endgame tablebases (EGTB) were developed. These tablebases provide perfect information about how to play out a position, determining whether it’s a win, draw, or loss with absolute certainty.

This post will explore what endgame tablebases are, their usage by chess engines and human players, and the likelihood of encountering tablebase positions in real games.

Endgame Tablebases are precomputed databases that contain every possible position in a given endgame scenario (with a specific number of pieces). They provide the exact evaluation and the best move for every position, assuming both sides play perfectly.

Each tablebase is categorized by the number of pieces on the board, and as the number of pieces increases, the complexity and size of the tablebase grow exponentially.

• 3-4-5 men EGTB: These contain positions with 3, 4, or 5 pieces on the board (including kings). These are fully solved and used in almost all modern chess engines.
• 6-men EGTB: This includes positions with 6 pieces and is also widely used by engines, though it's significantly larger than the 5-men databases.
• 7-men EGTB: These tablebases are the cutting edge of chess endgame analysis, but they require immense computational power and storage due to their size.

---

Usage of EGTB by Chess Engines and Humans

For Chess Engines:

Chess engines like Stockfish, Komodo, and Leela Chess Zero heavily rely on endgame tablebases to play perfectly in simplified endgame positions. Here's how they use them:

• 3-4-5 Men EGTB:

  • Almost universally used in chess engines. These tablebases are fast and light enough to be integrated into almost all chess engines.
  • Percentage of Usage: ~100% for engines once the position reaches this range. Engines rely on these databases to make perfect moves in endgames with 5 or fewer pieces.

• 6-Men EGTB:

  • Frequently used by top-tier engines. Since these require more computational resources, they are sometimes accessed through cloud-based systems rather than being stored locally.
  • Percentage of Usage: Around 90%, especially when reaching positions with 6 pieces. Engines seamlessly access these tablebases to ensure accurate calculations.

• 7-Men EGTB:

  • The most advanced tablebases currently in use, but due to their size (over 100 TB), only top-level engines can access them in real time. Most engines only use them when connected to online tablebases, which slows down the process slightly.
  • Percentage of Usage: 60-70% for the best engines in specific positions. Not all engines have access to these due to their massive size, but when available, they offer perfect information.

For Human Players:

Humans, even grandmasters, do not have direct access to these tablebases during a game, but they use them extensively in preparation and analysis. Here’s how humans interact with EGTB:

• 3-4-5 Men EGTB:

  • Strong players and grandmasters study positions from these tablebases to improve their endgame technique, but in practical play, most rely on pattern recognition rather than memorizing moves.
  • Percentage of Usage: ~10-20% in practical games, as positions with 5 or fewer pieces don’t occur frequently, and humans often don’t play them perfectly without assistance.

• 6-Men EGTB:

  • Fewer human players memorize these positions, but they are important for high-level play. A grandmaster might prepare specific 6-piece endgames, but it’s rare for a player to reach these positions in a real game.
  • Percentage of Usage: ~5-10% in practical games. These tablebases provide useful study material, but only rarely do such positions arise in competitive play.

• 7-Men EGTB:

  • Very few human players use 7-piece tablebases directly, as these positions are exceedingly rare in actual games. They are mostly used for academic purposes or engine analysis.
  • Percentage of Usage: ~1-2% in real games. While the technology is impressive, positions with 7 pieces that require perfect play are virtually impossible for humans to memorize or reach frequently.

---

Frequency of Encountering EGTB Positions in Practical Play

The likelihood of encountering an endgame that corresponds to a specific tablebase diminishes as the number of pieces increases:

1. 3-4-5 Men Endgames:

   • These positions occur with reasonable frequency in practical games, especially in simplified endgames where exchanges have taken place.
   • Percentage of Games: Around 5-10% of all games eventually reach a 5-men tablebase position.

2. 6-Men Endgames:

   • Positions with exactly 6 pieces are less common but still appear occasionally in tournament play, especially at the grandmaster level.
   • Percentage of Games: 1-2% of games reach a 6-men tablebase position, making them somewhat rare but still significant for engines.

3. 7-Men Endgames:

   • These positions are exceedingly rare in practical play due to the high likelihood of games finishing before the piece count drops to 7. When they do occur, they often involve complex combinations of pawns and pieces.
   • Percentage of Games: Less than 1% of games reach a 7-men tablebase scenario.

---

Conclusion: How Important Are EGTBs in Chess?

Endgame tablebases have revolutionized the way we think about the endgame. They allow engines to play perfectly and offer humans valuable insights for study and preparation. While humans rarely encounter these positions in practical play, they are critical for anyone who wants to master the endgame phase of chess.

For most players, the focus should be on mastering 3-5 piece endgames, as these occur most frequently. Top-tier engines, however, will continue to explore the vast complexity of 6- and 7-men positions, ensuring that the game of chess remains deeply fascinating and complex.

---

Key Takeaways:

• 3-5 men EGTB: Widely used by both engines and players. Practically every engine relies on these tablebases to play perfectly in endgames with fewer than 6 pieces.
• 6-men EGTB: Used by most high-level engines, but less frequently encountered by human players.
• 7-men EGTB: Cutting-edge technology that’s mainly for engine use and research, as these positions are almost never seen in real games.

If you want to improve your endgame, studying simplified positions with 3-5 pieces will yield the most benefit, as they are both common and crucial for converting winning positions or saving draws.