How many knights does it take to dominate a chess board
A video related to this sequence: https://oeis.org/A006075
Making better visuals using manim for these proofs:
http://www.contestcen.com/knproof.htm
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Comments
7.1
Short, interesting, and well-visualized. Keep up the good work.
5
The animation is helpful and I feel it moves at just the right speed. By the end of the video, I wished the narrative had moved just a bit more slowly, prompting me to pause and ponder how the larger boards could be solved.
It is not clear to me why the board pictured at the start of the video is 7-by-7 rather than a standard 8-by-8 chess board. Another chess-related question - and I know this video is an animation exercise for a puzzle taken as a given - is why the square the knight occupies would be included in what that squares that knight dominates. This is not intuitive, because a chess piece doesn't attack/defend its current square.
3.9
Really interesting video. I love the animation, and the topic was something I had never thought about but ended up being interesting. It was a little confusing how you found all of the "A" squares though (i.e. did you find them through trial and error or through some method).
6.2
I really liked your hook. It’s a simple problem that I can understand from the title alone. The manim animations were great, though sometimes I felt they took a little long to finish.
4.9
The problem is interesting, and I followed your reasoning clearly. I like that you used so many different techniques. Remember to define important terms (what do you mean by "dominate"?). It would help to have slightly longer transitions so it's clear when one thought ends and the next begins. And vary your tone a bit more (the monotone is a little distracting).
7
It's a really good entry, since it's a topic anyone can understand.
I will note that it would be interesting to make a video on the ideas behind a general n x n, rather than focusing on individual numbers.
4.1
4x4 : it is not clear that the sequence has to be increasing. It could happen that a knight exterior of the 3x3 board could light up the 3x3 center + some other that make it possible to cover the rest with only 2 knights.
Idea is simple, explanation are. Video is good, but not amazing imo.
7.2
Nice video ! You say that it took you a lot of time, and it really feels like it : the visuals are really good !
I’ve never heard of this problem before, and after watching this video twice, I understand the proofs of solutions for all boards up to 8x8.
The only thing is, in such a short time, it’s difficult to understand everything that quick. I would personally have preferred more explanations on the proofs. Like when you say “Since we know that we need 4 knights for the 3x3 board, we at least need 4 knights for the 4x4”, it’s not so evident ! We need (as a viewer) some time to understand why (and I still don’t understand why). Also, for the numbers in the grid, it may take some time to just understand “why?”. The arguments aren’t so clear, and I needed to pause or rewatch the video to finally understand by myself the purpose of the proof. For the others (6, 7 and 8 boards), just a simple phrase to explain : “we find a lower bound to the number of knights, and as we are able to reach it, it means that this is the number we were searching for”.
In conclusion, it’s a great video, with a lot of work into the visualisation, but not so clear in terms of explanations.
Scale :
- Motivation : 3
- Clarity : 3
- Novelty : 5
- Memorability : 5
---Total : 16
5.1
Overall nice presentation, but the scope could have been a bit wider. Also, the video ends very abruptly, and it would have been a bit nice to have some finishing comment to tie it all together. So, to summarize: the idea and presentation is nice, but would benefit from a deeper discussion.
7.2
Creative problem. Great video
5.2
Rating as "About the same"
I enjoyed this one. A good subject, well explained with nice graphics. However it did seem a little rushed - you could've easily made it twice as long and I think it would've been even better. I then would've rated it higher.
I would've preferred it if you had paused a few times to give the viewer an opportunity to prove the various sized boards themselves (don't be scared of silence and why not say pause the video here if you want to try proving it yourself).
Also you have written in the video description that there is a related OEIS sequence, but make no mention of it in the video itself. You could use the 1x1 and 2x2 cases as warm-up exercises for example. Why not finish by saying what is known about bigger boards.
Good video thanks
2.2
The proofs for 7 and 8 were not super clear as they moved too fast. It would be helpful to go slower on these, even though they are trivial; or show a method other than brute-force for determining this.
5.3
Outsanding graphics.
Interesting problem.
The explanations are clear overall.
What is lacking for me is how you came up with these proofs. I would have liked to be taken through the mathematical process and not just shown the proof.
6
In chess the square a piece is standing on is not considered to be controlled by this piece so it should not be counted. By doing so, the 3x3 square is impossible to cover but that's not really a problem, since we're most interested in the 8x8 chess board.
5.7
I like the video, but fail to see the math behind
3.8
Good motivation, good illustrations, and well-exposited proofs. But I kept waiting for some bigger picture (e.g. what can we say for larger n in general? can we give upper/lower bounds?), and it never came. The end of the video felt extremely abrupt.
One more minor comment: at 0:20, I would suggest defining "dominate" here (e.g. "attack or occupy"), rather than waiting until three sentences later to clarify.
7.8
Nice video. The motivation and problem statement are clear. It’s really easy to follow and well explained. I like the animations and the music. However, I think you should start using your own theme to differentiate yourself from others. Also, the way the video ends is a little abrupt; perhaps a final message or a promise of another video would improve it.
Thanks for the video, and keep creating amazing visualizations and proofs.