Exercise 18.2.5 in Database Systems The Complete Book was a daunting, double-exclamation-point problem. It felt impossible until I actually read the paragraph residing above the three constraints presented at the bottom of the problem.
I should read instructions more often. I wasted so much time trying to figure out why
"In S, T_1 precedes T_2" did not conflict with "In every serial schedule conflict-equivalent to S, T_2 precedes T_1". <-- (I disagree with the grammatical (syntactical?) rule that states that a double quote may not precede a period.)
On an unrelated note, I've discovered a wonderful website: http://www.cookingforengineers.com/