Questions tagged [logical-deduction]
A puzzle that requires formal logical deduction to arrive at the solution. This suggests more than merely reasoning through clues to find an answer (you might want [situation] for that).
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Connect the Pipes
Each pipe shown on the left (A through I) connects to exactly one pipe on the right.
To hide the answer, I have put a curtain over the pipe crossings and grayed out the pipe colors on the right side.
...
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Four prisoners wearing black and white hats
There are four prisoners. All four prisoners will be freed, if at least one of them correctly guesses the color of the hat on his head.
They can't speak to each other, and they can't touch each other.
...
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On which day The Joker usually going on a date?
You are an investigator. You are to investigate The Joker to know on which day he usually goes on a date with Harley Quinn. The Inspector said that The Joker is lying if and only if it's Monday, ...
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Ten Tricky Mathematicians
Somewhere on the Hyperbolic Plane, you encounter ten mathematicians. You know that some of them always tell the truth while the rest always lie. Each of them knows which of the others tell the truth ...
user18360
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Coin weighing problem
You are given ten stacks of golden coins, each stack consisting of ten coins and a digital scale with arbitrary precision.
You know that all stacks of coins are made from gold, weighing 10 grams per ...
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Brooklyn 99 riddle: Weighing Islanders [duplicate]
This one comes from this week's Brooklyn Nine-Nine episode!
There is an island with 12 islanders. All of the islanders individually weigh exactly the same amount, except for one, who either weighs ...
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Variation of 100 prisoners light problem
There is a classic problem below for which Dr. Yisong Song wrote a very well written and thought out series of solutions.
The variation here I've never seen anywhere but am curious. I want to work it ...
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New logical puzzle
The goal is to divide the grid into regions of exactly four cells (tetromino). Each region contains exactly two different symbols. Regions of the same shape must contain the same symbols. The ...
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3 Numbers on Hats, A = B + C
This feels like it should be a common puzzle, but I haven't found anything exactly like it searching online, so here goes. Apologies if it's a duplicate.
Three logicians, person 1, 2, and 3, along ...
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Chess Connect Puzzle
I made up a new logic puzzle based on the games Numberlink and Chess, and thought it ended up rather interesting. The solution, as usual, is unique.
The starting and ending positions of 7 chess ...
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This puzzle design was a DISASTER!
As any member of the PSE community knows, grid-deduction puzzles really aren't my forte.
In fact, I'd like to share one particularly disasterous attempt at designing a Slitherlink puzzle.
Disclaimer:...
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Statue View: Tetrominoes
This is a Statue View puzzle, an original invention combining two logic puzzle genres: Statue Park and Canal View.
Rules of Statue View:
Shade some cells of the grid to form the given set of pieces. ...
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Statue Park: Knight's Lines
This is a Statue Park puzzle.
Rules of Statue Park:
Shade some cells of the grid to form the given set of pieces. Pieces may be rotated or reflected.
Pieces cannot be orthogonally adjacent (though ...
- 146k
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Snakes and Adders - A New Grid Puzzle
So, literally last night, I dreamt of this new grid puzzle genre, so I'm just giving it a shot...
Rules of Snake and Adders:
Put some snakes into the grid on the white cells.
Each snake forms a ...
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4
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Who stole the flying car in Hogwarts?
During a trial in a Hogwarts court, Ron claimed that the Flying Ford Anglia car was stolen by Hermione.
Then Hermione and Harry gave testimonies which, for some reason, were not recorded. Later on ...
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Single Colour Mastermind Problem
Imagine we're playing a game of mastermind with the usual eight colours, only this version has six holes across in which to place colours. And to make it easier for you I tell you that I have filled ...
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Which box is safe to open?
One day, you enter your house...and find it has been burglarized. On the table, a note says, "Thank you for your valuables. In return, I left a gift in the basement." Quite confused, you ...
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My wall clock is not working
When I came back from my vacation I saw my wall clock has fallen down and not working. The clock was on the floor and all its numbers were detached from their positions. Can you help me to find out at ...
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Sum of secret numbers is 101
Alice, Bob, and Charlie were given three numbers, respectively. They were said that all the three numbers were positive integers and the sum was 101.
Alice: I know we have different numbers.
Bob: ...
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Heyawake: An Introductory Puzzle
This is a Heyawake ("divided rooms") puzzle.
Rules of Heyawake:
Shade some cells of the grid.
Shaded cells cannot be orthogonally adjacent; unshaded cells must be orthogonally connected.
...
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How do I tell the children's ages?
My friend once told me a logic puzzle along the lines of:
A student asks a teacher what the ages of the teacher's three kids are. The teacher said, "the product of their ages is 72, and the sum ...
user20
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votes
1
answer
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The Metaslitherlink
This puzzle is part of the Monthly Topic Challenge #13: Variety Slitherlinks.
Below is a grid containing multiple small slitherlinks. These can be independently solved to form clues for the large ...
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2
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Sudoku.... On your keyboard?
Tired of solving Sudokus on paper? Look no further! The solution is, literally, under your nose.
Why use a 9x9 grid, when you can use your own QWERTY keyboard!
RULES:
Fill each row with the numbers ...
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The Tree is Growing
I just found this new type of puzzle and I think the rule set is fun! So, I decided to create one.
Rules (taken from the original puzzle):
Create non-intersecting non-looping trees such that the ...
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votes
1
answer
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Another Straightforward 4-letters Crossword?
This is an entry for Fortnightly Topic Challenge #43: Variety Crossword Grids.
Across
4. "___ and on"
5. "La ___" light
6. Aside from it
8. Diagonal
10. Firefly
12. Clothes shop
...
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What's going on with this puzzle?
What is going on with this slitherlink puzzle with clues $2^3$?
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The answers to these questions are?
C is the correct answer to how many questions?
A. 1
B. 2
C. 3
D. 4
Which letter is the correct answer fewer times than any other?
A. D
B. B
C. C
D. A
Which letter is the ...
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1
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Stupendous Sponge
General Notes
This puzzle takes the form a 9×9×9 level-one Menger sponge
whose surface is divided into 648 1×1 cells. The aim is to draw
a single non-crossing loop along its surface by connecting the
...
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Which is worth more - a chest of nickels or half a chest of dimes?
I have two large identical chests of exactly the same shape, volume, etc. One is completely full of nickels (each worth 5 cents), and the other is exactly half full of dimes (each worth 10 cents). ...
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The Knight never lies, the knave always lies, and the spy either lies or tells the truth
A says he is not the knight, B says he is not a spy, and C says he is not the knave. Who is who?
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Can you open the door or die? v2
This is the follow up question to my previous question
You wake up and find yourself in a very strange room with a single
door. You find a note on the ground surrounded by lots of cards:
...
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Robots in a spaceship [duplicate]
Xerxes has 6, 7 and 8-arm robots in his spaceship. Unfortunately, the 7-arm robots are misprogrammed and everything they say is a lie. The other robots are fine, they always speak the truth.
Once ...
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Making a 9 digit number divisible by 11
Alice and Bob play the following game, taking turns. Alice starts and writes a non-zero single
digit number at the blackboard.
At every turn, each player adds a single digit at the right of the ...
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A man with two red pills and two white pills
Story:
A Color blind man is travelling in a somewhat famous ship that had just a few people on board. Everything was smooth sailing for some days.
One day,the man heard some noises from outside when ...
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What's in my pocket? [duplicate]
Well, I can tell you Johnny has memory cards in his pocket.
Back Story
My brother, Johnny, is a tech nerd. He loves gadgets of all kinds. As a matter of fact, you can be sure at any one given time, he ...
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Knights and knaves in Landilandia
You're traveling on a hiking trip in the land of Landilandia when you encounter a forest. The notes in your guidebook tell you that there's a safe route here leading into the woods, but when you ...
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Which one is the true statement? [closed]
All five statements below are true.
None of the four statements below are true.
Both of the statements above are true.
Exactly one of the three statements above is true.
None of the four statements ...
user58258
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Another pseudo-IQ question
This puzzle is part of the Monthly Topic Challenge #2: IQ Puzzle Parody
People keep asking me if there's anything between me and my good friend Ingrid Deduction... Well, it's... complicated... We go ...
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The mysterious card in the middle
The referee tells Lefty, Righty, and Middly: "I have picked three positive integers $L,M,R$ with $L<M<R$ and $L+M+R=13$, and I have written these numbers onto the three cards lying face down on ...
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Emeralds bet - A round world
It was the 15 October 1502, just a few hours before midnight in an old tavern at the docks. Emerald raised two fingers, after repeatedly looking at his three cards, before finally answering the ...
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Masyu jigsaw puzzle
Here's a masyu puzzle for you. The rules are as follows
Draw a single closed loop which does not cross or touch itself.
The sections of the loop run horizontally or vertically between the ...
- 3,662
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Edward and the seven imps' Game
Excerpt of “Manipulating the Fabric of Space”
“Miscasting translocation
spells can have many nasty consequences. The caster’s body could be
warped or torn apart, his soul could be separated ...
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When was Alice Born?
This is inspired by the following recent question: Living next door to Alice
Having failed to figure out where Alice lives, Bob and Charlie endeavour to determine the month in which Alice was born. ...
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What will the Frenchman say?
An Englishman, a Frenchman and a German are speaking.
First the Englishman says : "M".
Then the Frenchman says : "M" as well.
And the German also says : "M".
They all agree and decide to ...
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Isometric Heyacrazy - Now In 3D!
This is a Heyacrazy puzzle on an isometric grid.
Rules of Heyacrazy:
Shade some cells of the grid.
Shaded cells cannot be orthogonally adjacent; unshaded cells must be orthogonally connected.
When ...
- 146k
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The Illuminati and the Knights Templar
Some people in the American Senate are working for secret organizations. Some work for the Illuminati, some work for the Knights Templar, and some work for both. The are also innocent citizens who are ...
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Beans under the chessboard
Under every grid cell of a chessboard, I put either one bean or nothing.
Now if you choose a (grid) rectangular area on the chessboard, then I will tell you the parity of the number of beans under ...
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2
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Tackling The Triptych
Normal Sudoku rules apply. Numbers on thermometers must increase, starting from the bulb end. Killer clues indicate the sum of three digits in a cage, which cannot include repeated digits. In columns ...
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Someone has vandalised this long division. Can you reconstruct it?
Oh dear, someone has vandalised this long division.
They've replaced every digit either with a wrong digit or a hyphen.
Your task: reconstruct the entire thing. There's no remainder.
Please show all ...
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1
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Unbalanced weight of boxes
You are given a traditional balance scale with two pans (no reading) and 6 boxes with the following properties:
1) the weight of each box is a positive integer number
2) if you put any number of boxes ...
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