摘要：In this note, we discuss a supplementary explanation about works of Takahashi and Tanaka, which are a kind of replication study of Wilks & Meara (2002), where they discuss the structure of learners’ mental lexicon network from the viewpoint of psycholinguistics. Here we mainly discuss some mathematical structures which support their studies latently. Using some simple random graph techniques, we propose that the role of “densities” is important and useful under some suitable assumptions. Then, we exhibit the effectiveness of our method by applying it to the data of experiments in Takahashi and Tanaka, where some inequalities obtained mathematically help us to investigate some of the aspects of the L2 mental lexicon network. Mathematical proofs and detailed discussion are collected in the final section, in which we give also mathematical interpretation on some models which were shown by computer simulations in previous works.
