Separating Positive and Negative Data Examples by Concepts and Formulas: The Case of Restricted Signatures
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We study the separation of positive and negative data examples in terms of description logic (DL) concepts and formulas of decidable FO fragments, in the presence of an ontology. In contrast to previous work, we add a signature that specifies a subset of the symbols from the data and ontology that can be used for separation. We consider weak and strong versions of the resulting problem that differ in how the negative examples are treated. Our main results are that (a projective form of) the weak version is decidable in 𝒜ℒ𝒞ℐ while it is undecidable in the guarded fragment GF, the guarded negation fragment GNF, and the DL 𝒜ℒ𝒞ℱℐ𝒪, and that strong separability is decidable in 𝒜ℒ𝒞ℐ, GF, and GNF. We also provide (mostly tight) complexity bounds.
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