Dominoes 1

I wish I had a way to link to an Excel spreadsheet in this blog, but I don't see one.  Guess you'll just have to print this one out.

Dominoes rules

A set of dominoes has been laid out in a grid and the edges erased.  You must determine where the edges go.  The solution is unique.

Here is a sample and its solution:

Most puzzles will include a set of dominoes to the side for checking off used dominoes.  Unfortunately, I have not found a completely suitable domino applet yet.  www.puzzlepicnic.com has one, but it doesn't support the double nine dominos that I used for the first puzzle.

Edit: I know it has been years since I have posted anything on this site, but I decided to dust it off today and look at it.  When I did that, I noticed that there is a bit of a flaw in my sample puzzle, depending on your definition of the rules of a unique solution.  According to my definition, it is a flaw.  

The solution is not unique, in that everything can be solved uniquely up until the last four dominoes in the upper right corner.  The way I have the solution posted above is not a unique solution, as the 3/2, 3/1, and 2/1 dominoe can be moved around to provide another solution. In my definition of unique, this is not allowed and the mistake was mine as I did not intend the puzzle to work out this way.  However, the 1/1 domino can also be positioned vertically instead of horizontally, which leads to the following solution:

Working this way, we can see that this does force a unique solution.  So here's the rub: Some puzzlers consider the unique solution to be a condition that must be followed during the solving process, rather than a constraint on the solution, if that makes any sense.  The logic proceeds like this:  I have reached a point where I have to make a guess.  If I choose guess number one, the logic chain proceeding from that guess allows multiple solutions.  If I choose guess number two, the same thing could happen again.  Repeat until you get to the final guess.  This guess does lead to a unique solution.  Therefore, that must be the correct guess.  I don't really like this kind of puzzle.  For some reason, it just seems like the puzzle is cheating.  I like my puzzles to have one solution, and one solution only.  In fact, it wouldn't even be appropriate to say that my puzzle has a unique solution, because unique implies that one solution stands out different from the rest.  I would define the solution to my puzzles to be the solution.  I will leave this sample puzzle in the blog as it is for demonstration, but if you ever find one of my puzzles with a non-unique solution, please bring it to my attention, because that would've been an error in the design process.

Akari 1

 



 

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Akari Rules

Akari is a Japanese surname meaning "light."  The puzzle is also called Light-Up, and for obvious reasons once you try one.  Here are the rules.

1.The puzzle consists of a grid with some black cells and some white cells.  Some of the black cells contain numbers.
2. Light bulbs must be placed into the white cells.  The numbers in the black cells indicate how many horizontally and vertically neighboring cells contain light bulbs.  Black cells with no numbers can contain any number of neigboring bulbs.
3. Light bulbs illuminate all the cells in the row and column they are in, up to the edge of the grid, or to a black cell, whichever comes first.
4. No two light bulbs can illuminate each other.

Below are a sample puzzle and its only solution.

Nurikabe 4

It's been a long time (almost two years), but I've started creating puzzles again.  Maybe this time I'll be able to stick with it.

Nurikabe rules



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