The concept of Chu correspondences between formal contexts is introduced. The construction of formal concepts induces a functor $Gal$ from the category of Chu correspondences to the category of sup-preserving maps between complete lattices. It turns out that the category of Chu correspondences has a $*$-autonomous category structure and the functor $Gal$ is shown to preserve the $*$-autonomous category structure.
"Chu correspondences." Hokkaido Math. J. 37 (1) 147 - 214, February 2008. https://doi.org/10.14492/hokmj/1253539583