An argument that Merge is binary but its binarity refers to syntactic positions rather than objects.
In this book, Barbara Citko and Martina Gračanin-Yüksek examine the constraints on Merge—the basic structure-building operation in minimalist syntax—from a multidominant perspective. They maintain that Merge is binary, but argue that the binarity of Merge refers to syntactic positions Merge relates: what has typically been formulated as a constraint that prevents Merge from combining more than two syntactic objects is a constraint on Merge's relating more than two syntactic positions.