  We prove a new duality theorem for the category of precontact algebras which
implies the Stone Duality Theorem, its connected version obtained in
arXiv:1508.02220v3, 1-44 (to appear in Topology Appl.), the recent duality
theorems of Bezhanishvili, G., Bezhanishvili, N., Sourabh, S., Venema, Y. and
Goldblatt, R. and Grice, M, and some new duality theorems for the category of
contact algebras and for the category of complete contact algebras.
