Update README

Author: herohde

README.md

@@ -5,29 +5,32 @@ is currently mainly used to re-implement the following historical chess engines:
 
 ### TUROCHAMP (1948) by Alan Turing and David Champernowne
 
-Turochamp uses a full search with an unbounded
-quiescence search of "considerable moves" using material ratio and position play heuristics:
+Turochamp is an implementation of Turing's original "paper" chess engine. Turochamp uses a full
+search with an unbounded quiescence search of "considerable moves" using material ratio and position
+play heuristics:
 
 *  [turochamp-1ply](https://lichess.org/@/turochamp-1ply). Rating ~1300 (blitz/rapid).
-*  [turochamp-2ply](https://lichess.org/@/turochamp-2ply). Rating ~1600 (blitz/rapid).
+*  [turochamp-2ply](https://lichess.org/@/turochamp-2ply). Rating ~1400 (blitz/rapid).
 
 ### BERNSTEIN (1957) by Alex Bernstein, Michael de V. Roberts, Timothy Arbuckle and Martin Belsky 
 
-Bernstein uses a selective search of "plausible moves":
+Bernstein is a re-implementation of the first complete chess engine: Bernstein's chess program on
+the IBM 704. Bernstein uses a selective search limited to 7 "plausible moves" for computational feasibility:
 
-*  [bernstein-2ply](https://lichess.org/@/bernstein-2ply)
-*  [bernstein-4ply](https://lichess.org/@/bernstein-4ply)
+*  [bernstein-2ply](https://lichess.org/@/bernstein-2ply). Rating ~1200 (blitz/rapid).
+*  [bernstein-4ply](https://lichess.org/@/bernstein-4ply). Rating ~1400 (blitz/rapid).
 
 ### SARGON (1978) by Dan and Kathe Spracklen
 
-Sargon uses a full search with material exchange, king/queen pins and board control heuristics:
+Sargon is a re-implementation of Spracklens' early commercial chess engine. Sargon uses a full
+search with material exchange, king/queen pins and board control heuristics:
 
 *  [sargon-1ply](https://lichess.org/@/sargon-1ply). Rating ~1300 (blitz/rapid).
 *  [sargon-2ply](https://lichess.org/@/sargon-2ply). Rating ~1400 (blitz/rapid).
-*  [sargon-3ply](https://lichess.org/@/sargon-3ply). Rating ~1700 (blitz/rapid).
-*  [sargon-4ply](https://lichess.org/@/sargon-4ply). Rating ~1800 (blitz/rapid).
+*  [sargon-3ply](https://lichess.org/@/sargon-3ply). Rating ~1500 (blitz/rapid).
+*  [sargon-4ply](https://lichess.org/@/sargon-4ply). Rating ~1600 (blitz/rapid).
 
 Each engine can be played 24/7 for free on [lichess.org](https://lichess.org). They have quirks, blind spots and limitations,
 which is part of their charm -- and play at low search depths to entertain rather than win.
 
-_November 2023_
+_December 2023_

VERSION

@@ -6,6 +6,13 @@
 // Henning Korsholm Rohde <herohde@seekerror.org>
 //
 
+### 25. nov 2023; Version 0.90 ###
+  - Added BERNSTEIN. Running as "bernstein-2ply" and "bernstein-4ply" on lichess.org. Odd ply only due to no QS.
+  - Noticed that ratings are depressed after allowing bot opponents.
+
+TODO:
+  - Transposition tables are flawed. Disabled for now, but that limits sargon-3/4ply.
+
 ### 21. apr 2021; Version 0.89 ###
   - Added transposition tables and move ordering w/ hash hit.
   - Tweaked SARGON and TUROCHAMP evaluations based on dubious moves on lichess.

cmd/bernstein/bernstein/search.go

@@ -16,7 +16,7 @@ func (p PlausibleMoveTable) Explore(ctx context.Context, b *board.Board) (board.
 }
 
 func truncate[T any](list []T, limit int) []T {
-	if len(list) > limit {
+	if limit > 0 && len(list) > limit {
 		return list[:limit]
 	}
 	return list