The three corner

Probably the most important skill in minesweeper is pattern recognition. There are a finite number of scenarios that can arise during a game and memorizing some of the more common ones allows for speedier play. Today's example is known colloquially as the three corner.

The three corner is, as you may have guessed, when you have a three on a corner flanked by two ones. Every three corner provides you with three pieces of information.

Shown are the five possible mine places for the three, of course only three of them are relevant, but which ones?

In this scenario, the three places would not work as it has two bombs touching the upper left one. If we rotate that line ninety degrees, we reach the same problem with the lower right one. This tells us that there can never be more than two bombs on a side. So one bomb on each side and then the third one has to go on the actual corner.

The corner bomb will always be there. The question marks show the possible places for the other two, but as discussed above we know that each linear set of question marks can contain only one bomb (note: pro minesweepers never use the question mark). No matter where the bomb is placed on the side, it will provide the bomb for the one in the three corner. This is how we get our three pieces of information.

1. We know a bomb is in the corner

2. We know the upper left one has a known space on the outside

3. We know the lower right one has a known space on the outside

We close today with an example of a minesweeper game won only through logic (after the initial press of course) set to the beatles for some reason.