Mystery Master


Michael Benson

Fact Finder


Hello, I am an Artificial Linguistics Nanobot... but you can call me Alan. My objective is to give a general description of the Levels in the Mystery Master application. In games such as Ms. Pac-Man, you must successfully complete a level before you can play the next one. Mystery Master attempts the same thing, albeit without the raw thrills of the chase...

Mystery Master invokes each level to find marks. Only when a level is complete will it move on to the next level. While levels are used to find marks, laws are invoked on a mark to find additional marks. Think of it this way, when a mark is entered by a level, it is an action. When a mark is entered by a law, it is a reaction. Before you continue, please read the article on facts.

The examples I will use are taken from the logic puzzle "Five Houses". The levels are given below.

Level 1. Examine One Fact at a Time

Level 1 examines one fact at a time to enter one or more marks. This level has several parts to it. In essence, it starts with facts of type 1 (where the link is "with"), moves on to facts of type 2, then examines facts of type 3 and 4. Type 1 facts always yield exactly one mark, while the other types of facts usually yield more than one. This puzzle, along with most puzzles, does not have type 2 facts.

Level Changer

Below are the facts of type 3 or 4.

  1. The green house is directly to the right of the white one.
  2. The man who sings lives next to the man with the fox.
  3. The antiques collector lives next to the man with the horse.
  4. The Norwegian lives next to the blue house.

Level 2. Examine Two Facts at a Time

Level 2 examines two facts at a time to enter one or more marks. This level has several parts as well. In general, it looks at two facts at a time where the links for both facts have the same noun type. Logic puzzles that benefit from this level include: "Circus Anniversaries", "Fancy Footwear", "Hello Dolly!", "Mixed-Up Mythology", "The Seven Wives of Henri VII", "Six Fearsome Heroes", and "Witnesses".

Level 3. Examine n Facts at a Time

Level 3 examines n facts at a time to enter one or more marks. This level is for difficult puzzles such as "Hello Dolly!" and "The Seven Wives of Henri VII".

Level 4. Make Assumptions

Level 4 is the level of last resort. If a logic puzzle cannot be solved with its facts and rules, then assumptions must be made. Assumption is just a fancy word for guess, which is something you humans are good at. Usually assumptions are necessary for difficult puzzles. If the program makes an assumption, then finds there is a contradiction, the program must undo the assumption, and make another one. Even when the program finds a solution, it will undo the last assumption it made to see if there is another solution. The program will proceed in this manner until all possibilities have been exhausted. If there are multiple solutions, this usually means the puzzle module is not well defined.

Brain Scratcher

For more information, please read the article on assumptions.


Levels are how Mystery Master finds marks in a logical and systematic manner. You could learn a lot about solving logic puzzles by understanding how the levels work.

Please do that while I research a tomb raider named Lara Croft.