Editing Chess engine (section)

==Limiting an engine's strength==
By the late 1990s, the top engines had become so strong that few players stood a chance of winning a game against them.  To give players more of a chance, engines began to include settings to adjust or limit their strength.  In 2000, when [[Stefan Meyer-Kahlen]] and Franz Huber released the [[Universal Chess Interface]] protocol they included the parameters uci_limitstrength and uci_elo allowing engine authors to offer a variety of levels rated in accordance with [[Elo rating]], as calibrated by one of the rating lists.  Most GUIs for UCI engines allow users to set this Elo rating within the menus.  Even engines that have not adopted this parameter will sometimes have an adjustable strength parameter (e.g. Stockfish 11).  Engines which have a uci_elo parameter include [[Houdini (chess)|Houdini]], [[Fritz (chess)|Fritz]] 15–16, [[Rybka]], [[Shredder (software)|Shredder]], [[Hiarcs]], [[Junior (chess program)|Junior]], [[Zappa (chess)|Zappa]], and [[Sjeng (software)|Sjeng]].  GUIs such as [[Shredder (software)|Shredder]], [[Chess Assistant]], Convekta Aquarium,<ref>{{Cite web|url=https://shop.chessok.com/|title=ChessOK Shop, Software, Training, Equipment, Books|website=Shop.chessok.com|access-date=26 June 2022|archive-date=26 June 2022|archive-url=https://web.archive.org/web/20220626043458/https://shop.chessok.com/|url-status=live}}</ref> [[Hiarcs]] Chess Explorer, and Martin Blume's Arena<ref name="auto">{{Cite web |url=http://www.playwitharena.com/ |title=Free chess graphical user interface (GUI) Arena for chess engines |access-date=2018-11-29 |archive-url=https://web.archive.org/web/20070314030733/http://www.playwitharena.com/ |archive-date=2007-03-14 |url-status=dead }}</ref> have dropdown menus for setting the engine's uci_elo parameter. The Fritz family GUIs, [[Chess Assistant]], and Aquarium also have independent means of limiting an engine's strength apparently based on an engine's ability to generate ranked lists of moves (called multipv for 'principle variation').