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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2answers
45 views

Stuck on a minesweeper supposedly solvable through pure deduction

I'm playing minesweeper on a website that says you can win using pure deduction without guessing, and I am currently stuck in the top left corner of the map. It's a 30x16 grid with 170 mines and the ...
25
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1answer
604 views

Hokuro Puzzle: Introduction

This is an entry for Fortnightly Topic Challenge #44: Introduce a new grid deduction genre to the community. This puzzle type is inspired by Kakuro, and it has similar rules. Kakuro is short for '...
12
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1answer
342 views

Pentopia: One-way Crossing

This is an entry for Fortnightly Topic Challenge #44: Introduce a new grid deduction genre to the community. Here is a standard Pentopia puzzle. Rules of Pentopia: Place some pentominoes into the ...
8
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3answers
371 views

Tetrikabe: Hiding in the Corners

This puzzle is dedicated to Sciborg. Copying the dear gentleperson, some of the 4s are hiding in the corners. Rules: (Nurikabe section shamelessly stolen from an earlier puzzle by @jafe) Numbered ...
7
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1answer
110 views

Palette: A Multicoloured Grid Deduction Puzzle

This is an entry for Fortnightly Topic Challenge #44: Introduce a new grid deduction genre to the community. I've been dreaming up potential logic puzzles involving colours, and how they mix to form ...
11
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1answer
448 views

Dosun-Fuwari: an introduction

This is an entry for Fortnightly Topic Challenge #44: Introduce a new grid deduction genre to the community. I'm pleased to introduce you to the Dosun-Fuwari puzzle. Rules to fill the grid (translated ...
11
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1answer
312 views

Office Park: A Grid Deduction Puzzle

This is an entry for Fortnightly Topic Challenge #44: Introduce a new grid deduction genre to the community I had an idea for what I think is a new grid deduction puzzle which has some aspects of ...
16
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1answer
346 views

Norinori: QR-Code-ish

This is an entry for Fortnightly Topic Challenge #44: Introduce a new grid deduction genre to the community. Here is a standard Norinori puzzle. Rules of Norinori: Shade exactly two cells in each ...
13
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1answer
358 views

Hexagonal Nurikabe

Nurikabe is a popular grid puzzle, usually played on a square grid. Here is my attempt to adapt it to a hexagonal grid. To solve it, you must shade cells in the grid such that these conditions are met:...
13
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1answer
596 views

Tatamibari: an introduction

This is an entry for Fortnightly Topic Challenge #44: Introduce a new grid deduction genre to the community This is a Tatamibari puzzle, where you divide the grid into rectangles and squares. Rules ...
15
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2answers
597 views

Nurimisaki Puzzle: Introduction

This is an entry for Fortnightly Topic Challenge #44: Introduce a new grid deduction genre to the community This is a Nurimisaki puzzle, an area-connection puzzle. Rules of Nurimisaki (taken from ...
8
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1answer
298 views

A Sneaky Yin-Yang Puzzle

Here is a standard Yin-Yang puzzle. Rules of Yin-Yang: Fill each empty cell with either a black circle or a white circle. All white circles should be orthogonally connected, so do all black circles. ...
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0answers
129 views

4 Talking Clams, and treasure

After going to the depths of the ocean, you have finally reached it: the ultimate treasure of the world. However, when you go inside the sacred treasure room, you are presented with the Four Clams. ...
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0answers
113 views

Social Distancing Colors - A New Type of Puzzle? [closed]

I think I just thought of a new type of puzzle: Social Distancing Colors. Each of the colors in the rainbow represents at least how much one has to distance by: Red is 6m, Orange is 5m, Yellow is 4m, ...
17
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1answer
317 views

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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0answers
168 views

A monster slitherlink!

Does anyone want to have a stab at this monster slitherlink? Source: https://mellowmelon.wordpress.com/2010/03/17/puzzle-217/
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1answer
133 views

Another Yin Yang puzzle! Part two

I am sure this puzzle has only one solution. Also the solver of this puzzle can put up a Yin Yang puzzle if they wish to start a series. Rules of Yin-Yang: Fill each empty cell with either a black ...
6
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1answer
143 views

Three-and-Two (Santoitchi variant): Confused Knights

Three-and-Two is a variant of Santoitchi, where the shaded cells ("monominoes") are replaced by shaded dominoes. Rules: Shade some cells. The shaded cells should form dominoes (contiguous ...
13
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2answers
465 views

Slitherlink - A0, B1, C2, D3

The standard Slitherlink rules apply. However, first replace $A_1$, $A_2$, $B_1$, $B_2$, $C_1$, $C_2$, $D_1$, and $D_2$; such that the Slitherlink is uniquely solvable. Moreover, these equations must ...
14
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2answers
1k views

A slitherlink with only 3's

As we know, 3's seems to be very rare in slitherlinks. This is the slitherlink with only 3's.
38
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3answers
2k views

Animal Cross(word)ing

An entry in Fortnightly Topic Challenge #43: Variety Crossword Grids Each of the 40 clues listed below (a mix of pop culture and science/nature) yields the name of an animal. Your task is to solve ...
2
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1answer
157 views

Lost in this Loopy puzzle

I got this Loopy (Cairo) puzzle, but got stuck here: I have no idea how to proceed without guessing with backtracking. Are there any local deductions possible here?
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2answers
416 views

Another Yin-Yang puzzle

I saw someone post a ying-yang puzzle on here recently and I thought I might challenge people here with another one! Rules of Yin-Yang: Fill each empty cell with either a black circle or a white ...
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2answers
218 views

The blind one who sees all

A blind prisoner is offered a deal by a king. 3 monks will be sent to his cell over a period of three days,only one monk will be sent to the prisoner's cell on any day. The king may decide to send one ...
32
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2answers
1k views

Self-contained math crossword with if-then-else clues

An entry in Fortnightly Topic Challenge #43: Variety Crossword Grids Since I'm not good with with words and crosswords, here is a math crosswords: to know all the operands for the calculations you ...
13
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2answers
1k views

Yin-Yang: All-White

Here is a standard Yin-Yang puzzle. Rules of Yin-Yang: Fill each empty cell with either a black circle or a white circle. All white circles should be orthogonally connected, so do all black circles. ...
13
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1answer
378 views

Hetero-F(our|ive)-Cells

This is a hybrid of Four Cells and Five Cells (uses pentominoes instead of tetrominoes), with a global no-repeated-piece rule. Rules: The grid is to be divided along the grid lines into areas ...
1
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1answer
108 views

Who dances what musical genre and with whom?

The puzzle is as follows: 4 couples attended a magazine opening celebration party. These couples danced among themselves, all at the same time, to a disco suite, a pop ballad, a jazz tune and a waltz....
7
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2answers
494 views

An altered MineSweeper

I've been searching for an old project I did in college about a computer program to create and solve a special variation of the popular game MineSweeper where, instead of always one, you could have ...
8
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1answer
370 views

Four Cells: No Threes!

Four Cells is an area dividing puzzle. You may see an introduction to this puzzle here: Four Cells: An Introduction Rules of Four Cells: The grid is to be divided along the grid lines into areas ...
12
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1answer
600 views

A true no-no-gram

This is a nonogram with the usual rules. That is, you must fill white squares in with black so that the numbers at the head of each row or column indicate, in order, the respective lengths of ...
16
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1answer
412 views

Chain Puzzle: Tabletop Games #08 - Targui, or not Targui

This is the eighth Chain Puzzle in the Tabletop Games series, in which all puzzles are themed around board games, card games, tile games, and the like. The answer to this puzzle is a thematic word or ...
11
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1answer
292 views

Four Cells: An Introduction

This is a Four Cells puzzle, an area-dividing puzzle. Rules of Four Cells: The grid is to be divided along the grid lines into areas containing exactly four cells. A number in a cell indicates how ...
5
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1answer
96 views

Sjudoku II - A greater challenge in the world where 9 is 7

This is more difficult instance of a puzzle posted here. Rules similar to Sudoku applies: In each disk, the numbers 1,2,...7 should appear exactly once. No line may contain duplicate digits (note ...
20
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2answers
304 views

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 ...
7
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1answer
155 views

My two button microwave

Long ago, I encountered a microwave with a display in the "HH:MM:SS" format. But instead of a number pad, you entered the desired time through two buttons: An "up" button, which ...
2
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2answers
107 views

Next step/strategies for an Area 51 (Slitherlink variant) puzzle

I've been doing quite a few Slitherlinks recently (and puzzles containing Slitherlink elements, such as Area 51). I'm familiar with all the patterns described in the Wiki article but I feel like there'...
13
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1answer
427 views

Shingoki: An Exploration of Unicode

An entry in Fortnightly Topic Challenge #42: Wordless Connecting Walls-- wait, what? This is a Shingoki puzzle. The rules (paraphrased from puzzle-shingoki.com) are as follows: The aim is to form a ...
7
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2answers
389 views

Santoitchi: Crowded?

Santoitchi is yet another genre involving trominoes. The name seems to mean Three-and-One in Japanese with a deliberate misspelling (イッチ instead of the usual イチ for "one"). Here is an ...
5
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2answers
202 views

The children of the sultan

An old challenge from an old Portuguese book I have: Abdul Al-Kwaritz-Amuhmahd was a Arabic sultan who became very famous by the size of his harem and the number of children he had fathered. More so ...
9
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2answers
275 views

A 5-out-of-9 shading Nurikabe

Rules of Nurikabe: (copied from here) Numbered cells are unshaded. Unshaded cells are divided into regions, all of which contain exactly one number. The number indicates how many unshaded cells there ...
35
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4answers
2k views

Sjudoku - in a world where 9 is replaced by 7

Sjudoku (sju = seven in Swedish). Rules similar to Sudoku applies: In each disk, the numbers 1,2,...7 should appear exactly once. No line may contain duplicate digits (note that there are lines in 3 ...
7
votes
2answers
334 views

A half-shading Nurikabe

Rules of Nurikabe: (copied from here) Numbered cells are unshaded. Unshaded cells are divided into regions, all of which contain exactly one number. The number indicates how many unshaded cells there ...
12
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1answer
402 views

Tetrikabe: Socially Distanced Fours

Pentomino Nurikabe is still elusive, but here is another Tetromino Nurikabe! I'm not sure if the 4s are actually socially distanced enough. (The ones on the right and bottom are doing better than the ...
12
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5answers
2k views

How do you deduce complete list of the five beers you can drink, in this LSAT question?

I don't know if this is a real LSAT question, or if the author made it up, but my head already aches from looking at it! Does it have a valid solution? M Kimes. Ivy Briefs: True Tales of a Neurotic ...
4
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1answer
127 views

5x5 suko puzzle

Okay, an easy one. From 1 to 25, without repetition, fill the numbers into the grids. Rules of Suko: The four cells around each boxed number should add up to that number Each set of colored cells ...
10
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1answer
409 views

A Chaotik-Evil Encrypted Doppelblock

This is a birthday gift for my friend: Ivan a.k.a. chaotic_iak! ^^ As noted, you may need this clue if you want to solve this logically (otherwise, challenge yourself like Ivan):
6
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1answer
250 views

How to solve this Loopy puzzle efficiently with little backtracking?

I would like to solve this Loopy (Cairo) puzzle: But I would like to do so with as little backtracking as possible. By this I mean that I want to have at most one pending guess at a time; I do not ...
1
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1answer
95 views

How do you find the sum of the digits contiguous to one which is situated in a three by three table?

The problem is as follows: I am placing the numbers from 1 to 9 in the squares of a 3 x 3 board. I start by placing the numbers 1, 2, 3 and 4 as shown in the figure. For the number 5, the sum of the ...
11
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1answer
307 views

Tetromino Nurikabe: Five Fours

I enjoy combining polyominos with grid-deductions. My current plan is to create a Pentomino Nurikabe. But that sounds hard, so I made this Tetromino Nurikabe as practice first. I think it came out ...

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