5 ms·

Möbius-Strip Crosswords

81 points by ibobev 2mo ago

wxw 2mo ago
My partner publishes crosswords and it's always fun to see how much artistry goes into authoring a puzzle. You can play with the structure/grid, the theme of course, every minute detail of the fill, etc. Never would have thought of a Mobius-strip though, insane.
- rockostrich 2mo ago
  It's crazy how good puzzle creators are. I've watched a bunch of videos on it and I'm still in awe of how effortless they make it seem.
srean 2mo ago
A long long time ago I had a fun time making Mobius strip structure out of link list(s). Each edge of the ribbon was a linked list, connected to each other by rungs. It looped back on itself but connected crosswise . Then if you nuked all the rungs it was clear you still got a connected piece that you could traverse over.
wglass 2mo ago
Interesting article. Note that many of the clues in the article are mis numbered. Not sure why. Refer to the original puzzles linked for the correct clues.
- quuxplusone 2mo ago
  Oops! Should be fixed now.
edwcross 2mo ago
For anyone trying to solve the examples, the toroidal crosswords example image has a copy-paste error from the post author (not present in the original): the numbers for Down are 1, 3, 5 and 6 (and not 1, 2, 4, 7).
- quuxplusone 2mo ago
  (Author here.) Oops! and thank you. Should be fixed now. Happily I used SVG for those images, or it'd have been harder. :)
zem 2mo ago
qxw [https://www.quinapalus.com/qxw.html https://www.quinapalus.com/qxw.html] is a wonderful open source app that lets you make crosswords with interesting topologies, complete with grid filler support, if anyone wants to experiment with them.
unholiness 2mo ago
> if it actually wrapped around on itself with a half-twist, wouldn’t the letters wind up backwards too? Then 6-Down wouldn’t be MESSENGER but rather MESSENGER, and so on. This premise is assuming the Mobius strip is transparent, which the header image clearly isn't. No letter-reversals or any symmetry is needed. On normal, opaque paper, you can just make a crossword as a normal long loop. (proof: Write GGGGGGG on one side of a paper, and write it upside-down on the other side. With a twist, you'll get one long GGGGGGGGGGGGGG... looping as if it were one boring single-sided loop).
- arijun 2mo ago
  A true Mobius strip doesn't have "sides" like the paper model of one does. You can see that in the quote from Martin Gardner where he talks about a creature completing a loop becoming a mirror image with respect to it's friends. I assume the author wanted the paper model to mimic that property. Incidentally, the author's choice makes for a much more interesting puzzle than the one you would have them use (IMO)--yours would be indistinguishable from a puzzle written on a cylinder.
  - unholiness 2mo ago
    I agree it's an interesting puzzle! Just thought he made the jump to transparent paper without introduction in a way that confused me. It seemed instead like a non-transparent Mobius strip would join itself upside-down after a full loop, which wasn't obviously untrue.

81 points by ibobev 2mo ago

wxw 2mo ago

My partner publishes crosswords and it's always fun to see how much artistry goes into authoring a puzzle. You can play with the structure/grid, the theme of course, every minute detail of the fill, etc. Never would have thought of a Mobius-strip though, insane.

rockostrich 2mo ago
It's crazy how good puzzle creators are. I've watched a bunch of videos on it and I'm still in awe of how effortless they make it seem.

srean 2mo ago

A long long time ago I had a fun time making Mobius strip structure out of link list(s). Each edge of the ribbon was a linked list, connected to each other by rungs. It looped back on itself but connected crosswise . Then if you nuked all the rungs it was clear you still got a connected piece that you could traverse over.

wglass 2mo ago

Interesting article. Note that many of the clues in the article are mis numbered. Not sure why. Refer to the original puzzles linked for the correct clues.

quuxplusone 2mo ago
Oops! Should be fixed now.

edwcross 2mo ago

For anyone trying to solve the examples, the toroidal crosswords example image has a copy-paste error from the post author (not present in the original): the numbers for Down are 1, 3, 5 and 6 (and not 1, 2, 4, 7).

quuxplusone 2mo ago
(Author here.) Oops! and thank you. Should be fixed now. Happily I used SVG for those images, or it'd have been harder. :)

zem 2mo ago

qxw [https://www.quinapalus.com/qxw.html https://www.quinapalus.com/qxw.html] is a wonderful open source app that lets you make crosswords with interesting topologies, complete with grid filler support, if anyone wants to experiment with them.

unholiness 2mo ago

> if it actually wrapped around on itself with a half-twist, wouldn’t the letters wind up backwards too? Then 6-Down wouldn’t be MESSENGER but rather MESSENGER, and so on. This premise is assuming the Mobius strip is transparent, which the header image clearly isn't. No letter-reversals or any symmetry is needed. On normal, opaque paper, you can just make a crossword as a normal long loop. (proof: Write GGGGGGG on one side of a paper, and write it upside-down on the other side. With a twist, you'll get one long GGGGGGGGGGGGGG... looping as if it were one boring single-sided loop).

arijun 2mo ago
A true Mobius strip doesn't have "sides" like the paper model of one does. You can see that in the quote from Martin Gardner where he talks about a creature completing a loop becoming a mirror image with respect to it's friends. I assume the author wanted the paper model to mimic that property. Incidentally, the author's choice makes for a much more interesting puzzle than the one you would have them use (IMO)--yours would be indistinguishable from a puzzle written on a cylinder.
- unholiness 2mo ago
  I agree it's an interesting puzzle! Just thought he made the jump to transparent paper without introduction in a way that confused me. It seemed instead like a non-transparent Mobius strip would join itself upside-down after a full loop, which wasn't obviously untrue.