Clippers 4/21: Alex Erdmann on Unsupervised Morphological Acquisition

Given raw (in our case, textual) sentences as input, the Paradigm Discovery Problem (PDP) (Elsner et al., 2019, Erdmann et al., 2020) involves a bi-directional clustering of words into paradigms and cells. For instance, solving the PDP requires one to determine that ring and rang belong to the same paradigm, while bring and bang do not, and that rang and banged belong to the same cell, as they realize the same morphosyntactic property set, i.e., past tense. Solving the PDP is necessary in order to bootstrap to solving what’s often referred to as the Paradigm Cell Filling Problem (PCFP) (Ackerman et al., 2009), i.e., predicting forms that fill yet unrealized cells in partially attested paradigms. That is to say, if I want the plural of thesis, but have only seen the singular, I can only predict theses if I’ve solved the PDP in such a way that allows me to make generalizations regarding how number is realized.

Two forthcoming works address constrained versions of the PDP by focusing on a single part of speech at a time (Erdmann et al., 2020; Kann et al., 2020). For my dissertation, I am trying to adapt the system of Erdmann et al. (2020) to handle the unconstrained PDP by addressing scalability and overfitting issues which lock the system into poor predictions regarding the size of paradigms and prematurely eliminate potentially rewarding regions of the search space. This will be a very informal talk, I’m just looking to get some feedback on some issues I keep running into.