Encoding syntactic objects and Merge operations in function spaces
This work addresses the theoretical foundation for neurocomputational models of syntax, offering a mathematical framework that could impact linguistics and cognitive science, though it appears incremental in applying existing algebraic methods to syntax.
The paper tackles the problem of representing syntactic structures mathematically by showing that lexical items as functions in a function space can be faithfully represented, with Merge operations implemented via algebraic structures like Hopf algebras, and demonstrates a neurocomputational realization possibility. It includes a specific case using cross-frequency phase synchronization on sinusoidal waves to express Merge in terms of a semiring's successor function.
We provide a mathematical argument showing that, given a representation of lexical items as functions (wavelets, for instance) in some function space, it is possible to construct a faithful representation of arbitrary syntactic objects in the same function space. This space can be endowed with a commutative non-associative semiring structure built using the second Renyi entropy. The resulting representation of syntactic objects is compatible with the magma structure. The resulting set of functions is an algebra over an operad, where the operations in the operad model circuits that transform the input wave forms into a combined output that encodes the syntactic structure. The action of Merge on workspaces is faithfully implemented as action on these circuits, through a coproduct and a Hopf algebra Markov chain. The results obtained here provide a constructive argument showing the theoretical possibility of a neurocomputational realization of the core computational structure of syntax. We also present a particular case of this general construction where this type of realization of Merge is implemented as a cross frequency phase synchronization on sinusoidal waves. This also shows that Merge can be expressed in terms of the successor function of a semiring, thus clarifying the well known observation of its similarities with the successor function of arithmetic.