kernel sentence has a subject, simple verb, and possibly a direct object. The verb is always active (an action verb); helping verbs "to have" allowed; there are no adjectives or adverbs; it is always positive ("no" "not" prohibited)
The bear ate berries. (ate is action verb; the bear ate; the bear ate what? berries) A baby cried. (cried is action verb; a baby cried)
I've never heard of these before. See source for more details and some more examples.
