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[[FILE:SamuelBakLuna.jpg|border|right|thumb|link=http://chgs.elevator.umn.edu/asset/viewAsset/57f3b6787d58ae5f74bf8ba9#57f3b6d77d58ae5574bf8bb7|[[Arts#:Category:Samuel Bak|Samuel Bak]] - Luna <ref>[http://chgs.elevator.umn.edu/asset/viewAsset/57f3b6787d58ae5f74bf8ba9#57f3b6d77d58ae5574bf8bb7 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> ]]

Distortion is [[Hans Kmoch|Kmoch's]] term for horizontal splitting of pawns caused by advances. One may use something like this based on [[Pawn Fills|rearfill]], xor and [[Population Count|population count]] to get an idea of distortion. It considers the rank-difference of two file-adjacent pawns (if any) as distortion penalty - the higher the worse. [[Isolated Pawns (Bitboards)#IsolanisSetWise|Half-isolated]] or even [[Isolated Pawn|isolated pawns]] contribute a distortion penalty according to the size of their rearfill from 2 to 7 for each empty neighboring file, which discourages advancement of such pawns, interacting with terms considerring (half-) isolated pawns. Alternatively, for a "reverse" distortion penalty to encourage advancement of half-isolanis, one may use [[Pawn Fills|frontfill]] instead with a slightly different semantic is case of [[Doubled Pawn|doubled pawns]].