On functions defined on free Boolean algebras

We characterize measures on free Boolean algebras and we examine the relationships that exists between measures and binary tables in relational databases. It is shown that these measures are completely defined by their values on positive conjunctions and an algorithm that leads to the construction of measures starting from its values on a positive conjunction is also given, including a formula that allows the evaluation of measures for arbitrary polynomials. Finally, we study pairs of measures generated by ternary tables, i.e. by tables that contain missing or unknown values.