Computational Complexity of Multi-quantifier Sentences

We study the computational complexity of polyadic quantifiers in natural language. This type of quantification is widely used in formal semantics to model the meaning of multi-quantifier sentences. First, we show that the standard semantic constructions that turn simple quantifiers into complex ones, namely Boolean operations, iteration, cumulation, and resumption, are tractable. Then, we provide an insight into the operations yielding intractable natural language multi-quantifier expressions: branching and Ramseyfication. Next, we focus on a linguistic case study. We use computational complexity results to investigate semantic distinctions between quantified reciprocal sentences. We show a computational dichotomy between different readings of reciprocity. Finally, we go more into philosophical speculation on meaning, ambiguity and computational complexity. In particular, we investigate a possibility to revise the Strong Meaning Hypothesis with complexity aspects to better account for meaning shifts in the domain of multi-quantifier sentences. The paper not only contributes to the field of the formal semantics but also illustrates how the tools of computational complexity theory might be succesfully used in linguistics and philosophy with an eye towards cognitive science.