The shortest English sentence is probably "Go."   "Go" is an action verb and can be used in imperative mood, which means that it can be used with good, old "You Understood." So "Go" actually means "You go." On the other hand, if that interpretation doesn't strike your fancy, let's say that understood meanings are disallowed, then "I go" is the shortest sentence. "Go" doesn't require a complement since it is an action verb nor does it require a direct object. With a total of three letters—the same number as the illegal "I am" contender—"I go" should reign as the champion, unless someone out there knows of a single letter verb. (No fair pulling in Old English and foreign languages.)

Skipy