Logic Masters Deutschland e.V.

Red Light, Green Light (Dynamic Fog)

(Published on 18. March 2026, 14:04 by Hanks)

Many people seem to be enjoying the new clue types Triangle Inequality Lines and Anti-Triangle Lines that I introduced in my previous two puzzles. This time, I made another puzzle to combine both clue types together!

If you have not already, please do check out my previous two puzzles (see below). I hope you enjoy them, and they might help you become more familiar with the ruleset before tackling this more challenging puzzle :)




Rules:

Normal sudoku rules apply.

TRIANGLE INEQUALITY LINES: all digits on a red line are distinct. Furthermore, any three (not necessarily adjacent!) distinct digits {x,y,z} on a red line satisfy the Triangle Inequality, i.e., x+y>z, y+z>x, and z+x>y.

ANTI-TRIANGLE LINES: all digits on a green line are distinct. Furthermore, any three (not necessarily adjacent!) distinct digits {a,b,c} on a green line do not satisfy the Triangle Inequality, i.e., the sum of the two smaller digits in {a,b,c} is less than or equal to the largest digit in {a,b,c}.

DYNAMIC FOG: entering a correct digit clears fog in its cell, and may or may not clear fog in other cells.




My previous puzzles:

PUZZLE 1: x+y>z (Dynamic Fog)

PUZZLE 2: a+b<=c (Dynamic Fog)

This puzzle:

PUZZLE 3: Solve online




Solution code: Digits in column 9


Solved by kublai, illegel, SKORP17, Big Tiger, MaxSmartable, kangaroo, jkuo7, WvdWest, neica, MattJones, mjhoffman, Elliott810, mew_rocks, MikeMeech, Tulrak, Khatru, Senjo, CyreneDuVent, EFlatMinor, wuc, Raistlen, Vaurien, zeniko, ksm020610, Morisenseiisgod, madhupt, seaweed, FrauHoppmann, pescirope, jinkela114514, QuiltyAsCharged, OGRussHood, ABCDwp, Exigus, Uhu, xbw_________, thedeanster
Full list

Comments

on 28. April 2026, 16:16 by xbw_________
Tricky rules, Great problem!! Not so hard but cool for me

on 5. April 2026, 23:09 by wuc
Got me thinking for a long time. To me 4*. Tricky ruleset.

on 5. April 2026, 14:01 by MikeMeech
Now that was a cool new ruleset!

on 26. March 2026, 08:39 by MattJones
Magnificent! Tricky in parts, and such clever setting. Thank you!

on 18. March 2026, 22:46 by Big Tiger
Good heavens - Future solvers, pay attention: You WILL get confused and start to do "the maths" wrong because you'll forget which line does what! I did accidentally reveal some fog because of my mental mistakes but I made myself go back and prove each step correctly. I'd say at least 3 stars.

on 18. March 2026, 16:20 by kublai
Is he triangle man? Or is he particle man? As we know, if they have a fight, triangle wins. But at least some great puzzles come out of it!

Difficulty:4
Rating:96 %
Solved:37 times
Observed:1 times
ID:000RY2

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Solution code:

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