RoccondilRinon said:

It's debatable, really. The films weren't explicitly planned so that act one ends here or there. An act break can come at any change in the story, and I think it's more a matter of the feel of the film than Significant Character Decisions.

Well, our opinions are debateable, the three-act structure isn't. If TPM does have four acts, then that's yet another reason it fails.

If act two of ROTJ ends with Luke handing himself over, act three begins with the Rebel fleet. Your point being?

My point being exactly what I said. Clearly I was referring to Luke's decision to face Vader and the Emperor. Act changes have absolutely nothing to do with a scene break, and everything to do with the actions/motivations of the characters. Go ahead and ask any working screenwriter, and then discuss it. I don't mean that to sound conceited, arrogant or whatever, but that's screenwriting. Act II and Act III transition at exactly the same point, not the CUT TO the next scene.