Algebras of distributions of binary isolating formulas of a complete   theory
  We define a class of algebras describing links of binary isolating formulas on a set of realizations for a family of 1-types of a complete theory. We prove that a set of labels for binary isolating formulas on a set of realizations for a 1-type p forms a groupoid of a special form if there is an atomic model over a realization of p. We describe the class of these groupoids and consider features of these groupoids in a general case and for special theories. A description of the class of partial groupoids relative to families of 1-types is given. 
Ilya V. Shulepov and Sergey V. Sudoplatov
math.LO