All posts by Teun Spaans

About Teun Spaans

Hi, I'm a puzzle collector & designer. I have collected and designed puzzles for about 30 years, though not with great intensity. Other stuff: my blog about plants and nature my professional blog my website

Christmas 2017


Dominosas are puzzles where the dominoes have been shuffled and turned face up. All the numbers are given, but the borders between the dominoes are not given – these have to be solved by the reader.
I used to publish quarterly on them at my site domino plaza.

Usually a 6×6 set of dominoes is used, though larger or smaller sets can be used.

Here are two examples:
1) The christmas bauble**/*****


2) The church****/*****


You can check your solution here

3) Solving strategies
a) Counts
Make a count of how often all combinations appear. To do so, list all dominoes and how often they appear in the puzzle:
0-0: 2
1-0: 3
1-1: 5
2-0: 2
2-1: 1
2-2: 3
and so on.
This will give you the position of 2-1. Mark the borders on the printed puzzle.

b) Cross off deleted connections



Continuing the above example, it is easy to jump to a conclusion about 3-3, but before that we have some bookkeeping to do. Identifying the domino severed a number of links. In our example the severed links are the 3-1, 6-1, 2-0, and 5-2. When we update our list above for these severed links, we find that the number of 2-0 combinations is now reduced to 1, giving another domino.

c) Unique positions.



In this diagram, it is easy to see that in the top left position, only-the 3-3 is possible.

d) Block impossible links
Identifying the 3-3 domino blocks the link between all other 3-3 combinations:



This in turn, will in some situations trigger another situation like in step c)

New puzzles are published at least twice a month on Fridays. Solutions are usually published after one or more weeks.

External links:
https://www.puzzle-dominosa.com/ – play them online
https://www.chiark.greenend.org.uk/~sgtatham/puzzles/js/dominosa.html – another online game site
http://medmunds.github.io/puzzles/dominosa.html – 3rd in line play
https://play.google.com/store/apps/details?id=com.oxothuk.dominosa – android app
http://www.mathematica-journal.com/2014/10/three-ways-to-solve-domino-grids/ – three ways to solve them.

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Bongard problem colours


The Russian scientist M.M. Bongard published a book in 1967 that contains 100 problems. Each problem consists of 12 small boxes: six boxes on the left and six on the right. Each of the six boxes on the left conform to a certain rule. Each and every box on the right contradicts this rule. Your task, of course, is to figure out the rule.

Bongard problem colours**/*****

You can check your solution here

You can find more Bongard problems here and at Harry Foundalis site, and in the category ‘Bongard problems’ in the right margin of this page.

New puzzles are published at least twice a month on Fridays. Solutions are published after one or more weeks. You are welcome to remark on the difficulty level of the puzzles, discuss alternate solutions, and so on. Puzzles are rated on a scale of 1 to 5 stars.

Next month I intend to publish a Christmas special.

Hidden numbers


In issue @@@ of @@@, Sanders published a new type of puzzle, called ‘hidden numbers’.

I must confess that the puzzle was too hard for me, though in the future I may give it a try again.

In this post I present a simplified version.
1. The numbers 1 to n have been hidden in a square grid.
2. Yellow areas give the sum of the hidden numbers in row and column of the yellow square.

Example:


1) 4×4*/*****


2) 5×5*/*****


3) 6×6**/*****


From here there are two ways to increase the difficulty of the puzzle (aside from increasing the size):
a) Put more than one hidden number in a row and / or column. This is what Sanders did.
b) Sum only the first number visible in any row or column. Any number, including the numbers in yellow squares, block the line of sight for any numbers behind them.

New puzzles are published twice a month on Fridays. Solutions are published after one or more weeks. You are welcome to discuss difficulty levels, variations and alternate solutions, but plz. don’t publish the solutions.

The ancient tablet


1) The ancient tablet**/*****
Some archeologists discovered an ancient tablet. After a concerted effort, the managed to translate four sentences:
Baruntas glizaval kama – the golden crown is hidden
Glu kama valet – the golden bracelet is revealed
Glizaval glu kazu – silver crown is revealed
Baruntas kazu valet – Silver bracelet is hidden

What does “kama valet baruntas” mean?

You can check your solution here

New puzzles are published at least twice a month on Fridays. Solutions are published after one or more weeks. You are welcome to remark on the difficulty level of the puzzles, discuss alternate solutions, and so on. Puzzles are rated on a scale of 1 to 5 stars.

If you like this puzzle, you may be interested in my book with similar ouzzles.

Bongard problem 13


The Russian scientist M.M. Bongard published a book in 1967 that contains 100 problems. Each problem consists of 12 small boxes: six boxes on the left and six on the right. Each of the six boxes on the left conform to a certain rule. Each and every box on the right contradicts this rule. Your task, of course, is to figure out the rule.

Bongard problem 13**/*****


You can check your solution here

You can find more Bongard problems here and at Harry Foundalis site, and in the category ‘Bongard problems’ in the right margin of this page.

New puzzles are published at least twice a month on Fridays. Solutions are published after one or more weeks. You are welcome to remark on the difficulty level of the puzzles, discuss alternate solutions, and so on. Puzzles are rated on a scale of 1 to 5 stars.

Cryptarithm – trees


Cryptarithm – trees***/*****
Both summations below can be translated into a correct sum by replacing every letter with a digit. The same letter always stands for the same digit and the same digit has always been replaced by the same letter.

cryptarithm-trees-exercise

You can check both your solution here

New puzzles are published at least twice a month on Friday. Solutions are published after one or more weeks. You are welcome to remark on the difficulty level of the puzzles, discuss alternate solutions, and so on. Puzzles are rated on a scale of 1 to 5 stars.

Matchsticks – hexagon


Last month we looked at some hexagon matchstick puzzles, and this month features some more.

1) Move 4 matches**/*****
From the figure above, move 4 matchsticks so that you have 4 triangles on unequal size.

2) Move 4 matches***/*****
From the figure above, move 4 matchsticks so that you have 6 triangles again.

You can check your solutions here and here.

New puzzles are published at least twice a month on Friday. Solutions are published after one or more weeks. You are welcome to remark on the difficulty level of the puzzles, discuss alternate solutions, and so on. Puzzles are rated on a scale of 1 to 5 stars.

Round about


1) Nr 1**/*****

1 Uttered short, shrill sound
2 occurring more typically than an alternative form
3 place for keeping explosives
4 found in the earthcrust
5 give and receive reciprocally
6 make anew
7 follow along behind
8 live forever
9 more than opponents
10 leave country

The letters around each numbered square are an anagram of the numbered clue.
The numbered squares should be filled with the first letter of each word of the solution
Together, the letters form a word.

This puzzle is a variation on the “Blokje om” puzzle, in Visie 2017 nr 16. Visie (vision) is a magazine published by de Evangelische Omroep (Evangelical Brodcast) in The Netherlands.

You can check your solution here

New puzzles are published at least twice a month on Friday. Solutions are published after one or more weeks. You are welcome to remark on the difficulty level of the puzzles, discuss alternate solutions, and so on. Puzzles are rated on a scale of 1 to 5 stars.

Bongard problem 33


The Russian scientist M.M. Bongard published a book in 1967 that contains 100 problems. Each problem consists of 12 small boxes: six boxes on the left and six on the right. Each of the six boxes on the left conform to a certain rule. Each and every box on the right contradicts this rule. Your task, of course, is to figure out the rule.

Bongard problem 34**/*****


You can check your solutions here

You can find more Bongard problems here and at Harry Foundalis site, and in the category ‘Bongard problems’ in the right margin of this page.

New puzzles are published at least twice a month on Fridays. Solutions are published after one or more weeks. You are welcome to remark on the difficulty level of the puzzles, discuss alternate solutions, and so on. Puzzles are rated on a scale of 1 to 5 stars.