This document summarizes chapter 5 of Radford's 1997 book on syntax. It discusses:
1) Interpretable and uninterpretable features that words carry and how they are checked against each other through syntactic operations. Features like case, agreement and tense are uninterpretable at logical form while features like number and person are interpretable.
2) The process of checking involves matching the features that heads impose on their specifiers and complements. Checking erases uninterpretable features to satisfy full interpretation.
3) Examples show how checking works in grammatical sentences and fails in ungrammatical ones. Modals like can impose person-neutral nominative subjects and infinitival complements.
4) Ph