I recently watched this video which presents a deduction "riddle" about dragon jousting. The rules for the puzzle (from the video) are as follows:
After centuries of war, the world’s kingdoms have come to an agreement. Every five years, teams representing the elves, goblins, and treefolk will compete in a grand tournament of dragon jousting. Every team will face each of the others once. The kingdom whose team wins the most matches will rule all of Center-Realm until the next tournament. [...]
You’ve been given the extremely important job of recording the scores for the first inaugural tournament. But the opening celebrations get a bit out of control, and when you wake up, you realize the games are already underway. Fortunately, no one has noticed your absence so far. However, you need to get up to speed quickly; if your boss, the head tournament official, finds out you’ve been sleeping on the job, you’ll lose your head.
After weighing your options, you decide to offer your life’s savings to [a wizard] in return for the information, giving him your blank scorecard to fill out. But before he can finish, your boss walks into the tent. You barely manage to hide the scorecard in time, and the wizard excuses himself.
Your boss chuckles. “Hope you didn’t believe anything Gorbak’s been saying— he’s been cursed to tell only lies, even in writing. Anyway, can you believe how low-scoring the tournament’s been? Every team has played at least once, yet not a single match with a combined score of more than [five points]! Anyhow, I’ll be back in a minute to review your scorecard.” You laugh along, and when he leaves you look at the partially completed card, now knowing every single number on it is wrong.
Along with the rules you get the partially filled scorecard with 6 columns and a row for each of the three teams.
The columns are:
Number of games played
Number of games won
Number of games lost
Number of games tied
Total points scored across all games by the team of the row
Total points scored across all games by opponents of the team of the row
The scorecard given in the video is
1 0 _ _ 6 _ 2 _ _ 1 0 3 _ _ _ 0 0 1
However the top left square doesn't need to be filled out to solve the puzzle so the card
_ 0 _ _ 6 _ 2 _ _ 1 0 3 _ _ _ 0 0 1
Would have been just as informative.
So this begs the question what is the fewest number of squares that Morbak could fill out in a scorecard such that the correct scorecard could be deduced? The solution to the puzzle does not have to be the same, it just has to be deducible from the start of the puzzle.