A new concept of model for the US-tense logic is introduced, in which ternary relations of betweenness are adjoined to the usual early-later relation. The class of these new models, which contains the class of Kripke models, satisfies, contrary to that, the Distinguishable Model Theorem, in the sense that each model is equivalent to a model in which no two points verify exactly the same formulas.
"A Distinguishable Model Theorem for the Minimal US-Tense Logic." Notre Dame J. Formal Logic 36 (4) 585 - 594, Fall 1995. https://doi.org/10.1305/ndjfl/1040136918