Actually, after the engineer has finished, the mathematician wakes up, sees the fire going out and a smoldering ember burning the corner of his notes.
He immediately empties his whiskey bottle, pours out the contents all over the room, lights a match and goes back to bed...
...secure in the knowledge that he has reduced it to a previously-solved problem.
LOL, I'm sharing that joke and your addendum with my boss ( mathematician who wrote the Apollo trajectory software).