Restricted number and stubborn dative: Long-distance agreement across Basque nominalised complement clauses

In varieties of Basque, objects embedded into absolutive- and dative-marked nominalised complement clauses can enter a long-distance agreement relation with the matrix auxiliary. The observed patterns are derived from the featural specifications and probing characteristics of different types of matrix probes: absolutive clauses appear opaquer because they are targeted by a person and a number probe, the former restricting the range of possible goals for the latter, while dative clauses seem more transparent because they are targeted by an integral probe, which, as a consequence of its integrity, is ‘stubborn’, and able to penetrate domains inaccessible to singlefeature absolutive probes.