  The widespread usage of latent language representations via pre-trained
language models (LMs) suggests that they are a promising source of structured
knowledge. However, existing methods focus only on a single object per
subject-relation pair, even though often multiple objects are correct. To
overcome this limitation, we analyze these representations for their potential
to yield materialized multi-object relational knowledge. We formulate the
problem as a rank-then-select task. For ranking candidate objects, we evaluate
existing prompting techniques and propose new ones incorporating domain
knowledge. Among the selection methods, we find that choosing objects with a
likelihood above a learned relation-specific threshold gives a 49.5% F1 score.
Our results highlight the difficulty of employing LMs for the multi-valued
slot-filling task and pave the way for further research on extracting
relational knowledge from latent language representations.
