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[[FILE:SamuelBak_King.jpg|border|right|thumb|link=http://chgs.elevator.umn.edu/asset/viewAsset/57f3b6787d58ae5f74bf8ba9#57f3b6d77d58ae5574bf8bb0|[[:Category:Samuel Bak|Samuel Bak]] - King <ref>[http://chgs.elevator.umn.edu/asset/viewAsset/57f3b6787d58ae5f74bf8ba9#57f3b6d77d58ae5574bf8bb0 Chess in the Art of Samuel Bak], [http://www.chgs.umn.edu/ Center for Holocaust & Genocide Studies], [https://en.wikipedia.org/wiki/University_of_Minnesota [University of Minnesota]]</ref> ]]

This kind of algorithm is used by [[Crafty]]. Another, perhaps more basic example is the [[CPW-engineEngine]] as implemented in [[CPW-Engine_eval]], and the one demonstrated in the [[Evaluation Function Draft]].<span id="VMOB"></span>=Virtual Mobility=Another heuristic is to temporary replace the king by a [[Queen|queen]], to use her virtual [[Mobility|mobility]] as a measure of opponent's [[Sliding Pieces|sliding piece]] [[Sliding Piece Attacks|attacking]] chances and therefore an unsafe king.One may even temporary modify the [[Occupancy|occupancy]] to improve this virtual mobility, e.g by removing mobile opponent pieces.

King zone is usually defined as squares to which enemy King can move plus two or three additional squares facing enemy position. Basic King safety function, similar to the one described in [[Toga Log#UserManual|Toga log user manual]], can work as follows: we have two variables, '''attackingPiecesCount''' and '''valueOfAttacks''', zeroed at startup. If a piece attacks enemy king zone, we increase attackingPiecesCount by one, and count how many squares within enemy King zone are attacked. We multpily the number of attacked squares by a constant: 20 for a knight, 20 for a bishop, 40 for a rook and 80 for a queen. The result of multiplication is added to valueOfAttacks. After finding all attacks, we look at attackingPiecesCount, use it as an index to the table given below, and our king attack score is <br/> '''(valueOfAttacks * attackWeight[attackingPiecesCount] ) / 100'''.

The most elaborate king safety evaluation schemes gather information about [[Square Control|control of the squares]] near the enemy king. A good explanation of such an algorithm might be found on [[Ed Schroder|Ed Schröder's]] ''Programmer Corner'' <ref>[http://www.top-5000.nl/authors/rebel/chess840.htm [Rebel#ProgrammerCorner|Programmer Corner] by [[Ed Schroder|Ed Schröder]], King Safety in REBEL</ref> <ref>How Rebel Plays Chess is also available as [http://members.home.nl/matador/Inside%20Rebel.pdf pdf]</ref>. If a program, unlike [[Rebel]], does not keep [[Incremental Updates|incrementally updated]] [[Attack and Defend Maps|attack tables]], this knowledge is likely to be uncovered while calculating [[Mobility|mobility]].

* [[King Pattern#KingSafety|King Safety]] in [[King Pattern]] with [[Bitboards]]

* [[Videos#:Category:The Rolling Stones|The Rolling Stones]] - [https://en.wikipedia.org/wiki/Gimme_Shelter Gimme Shelter] (1998 promotion video), [https://en.wikipedia.org/wiki/YouTube YouTube] Video: [https://en.wikipedia.org/wiki/Bridges_to_Babylon_Tour_%2797%E2%80%9398 Bridges to Babylon Tour] feat. [https://en.wikipedia.org/wiki/Lisa_Fischer Lisa Fischer] and [[Videos#DarrylJones:Category:Darryl Jones|Darryl Jones]], et al., December 12 1997, [https://en.wikipedia.org/wiki/The_Dome_at_America%27s_Center Trans World Dome], [https://en.wikipedia.org/wiki/St._Louis St. Louis] [https://en.wikipedia.org/wiki/Missouri Missouri]