A Chu space is a binary relation from a set 
to an antiset 
which is defined as a set
which transforms via converse functions.
Chu Space
See also
AntisetExplore with Wolfram|Alpha
References
Stanford Concurrency Group. "Guide to Papers on Chu Spaces." http://boole.stanford.edu/chuguide.html.Referenced on Wolfram|Alpha
Chu SpaceCite this as:
Weisstein, Eric W. "Chu Space." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/ChuSpace.html