Final answer:
The irony of Charlie reading Vrostadt's equations on levels of semantic progression for learning how to communicate is that he struggles with language and communication himself.
Step-by-step explanation:
The irony of Charlie reading Vrostadt's equations on levels of semantic progression for learning how to communicate is that Charlie, who has a learning disability, struggles with language and communication. This makes it ironic that he is trying to understand complex equations about language development. It is also ironic because Charlie's progress in learning how to communicate is not represented by reading academic equations, but rather through his personal experiences and interactions with others.