What is a dede sentence?

There is no grammatical term or concept called a "dede sentence." It's likely a misspelling or a made-up term.

Please provide more context or information about where you encountered this term. For example:

* Where did you see or hear "dede sentence"? (e.g., a book, website, conversation)

* What was the surrounding text or conversation about?

* What do you think "dede sentence" might mean?

With more context, I can better understand what you're asking and offer a helpful response.