December 2nd, 2024

Optimality of Gerver's Sofa

Jineon Baek's paper "Optimality of Gerver's Sofa" resolves the moving sofa problem, demonstrating Gerver's construction achieves a maximum area of approximately 2.2195, contributing to metric geometry and optimization.

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Optimality of Gerver's Sofa

The paper titled "Optimality of Gerver's Sofa" by Jineon Baek addresses the moving sofa problem in metric geometry. The author demonstrates that Gerver's construction, which consists of 18 curve sections, achieves the maximum area of approximately 2.2195. This result resolves a long-standing question in the field regarding the optimal shape for a sofa that can be maneuvered around a right-angled corner while maximizing area. The paper spans 119 pages and includes 21 figures to illustrate the findings. The work falls under several mathematical classifications, including metric geometry, combinatorics, and optimization.

- The paper resolves the moving sofa problem.

- Gerver's construction is shown to have the maximum area of approximately 2.2195.

- The study includes 119 pages and 21 figures.

- The research contributes to the fields of metric geometry and optimization.

AI: What people are saying
The discussion surrounding Jineon Baek's paper on Gerver's Sofa reveals various perspectives on the moving sofa problem and its implications.
  • Many commenters express excitement about the resolution of a long-standing mathematical problem, with some noting its historical significance.
  • There are inquiries about the proof's peer review status and its practical applications, indicating a desire for validation and real-world relevance.
  • Some users share personal anecdotes or humorous takes related to the sofa problem, highlighting its accessibility and relatability.
  • Comments also touch on the technical aspects of the proof, including the use of computer assistance and the complexity of the shape's definition.
  • Several users question the practicality of the findings, suggesting that real-world furniture moving involves additional dimensions and considerations.
Link Icon 19 comments
By @senkora - 5 months
Here's a fun render of how a real life Gerver's Sofa could look:

https://www.mdpi.com/symmetry/symmetry-14-01409/article_depl...

I kinda want one...

Source: https://www.mdpi.com/2073-8994/14/7/1409

By @doormatt - 5 months
For those that don't understand - https://en.wikipedia.org/wiki/Moving_sofa_problem
By @n4r9 - 5 months
Looks like the author researched this during their PhD which ended this year, obtained a postdoc and then finished it off. Good on them!

I wonder how the result varies if one of the corridors (the second one for simplicity) is given a variable width. And if the angle of turn is variable.

By @yoshicoder - 5 months
I am not well versed with mathematics publishing, but has this proof been already been peer reviewed by other mathematicians, or is it still awaiting confirmation/proof replication?
By @ks2048 - 5 months
I was trying to search in the paper for a definition of the shape, to, for example, draw it in SVG.

It seems there is no closed-form solution. I saw this paper is maybe easier to follow for the definition:

https://www.math.ucdavis.edu/~romik/data/uploads/papers/sofa...

Quote:

It is worth noting that Gerver’s description of his shape is not fully explicit, in the sense that the analytic formulas for the curved pieces of the shape are given in terms of four numerical constants A, B, φ and θ (where 0 < φ < θ < π/4 are angles with a certain geometric meaning), which are defined only implicitly as solutions of the nonlinear system of four equations

By @ajb - 5 months
Interesting, but not practical. All real furniture movers would make use of the third dimension.

The difficulty of extending the definition to 3 dimensions is that the restriction to 2 separates two classes of constraint: being able to move the sofa round the corner, and the shape of the sofa being comfortable to sit on.

By @phamilton - 5 months
I introduced my kids (13 and 11) to the sofa problem last week as we installed this cabinet organizer from IKEA: https://www.ikea.com/us/en/p/utrusta-corner-base-cab-pull-ou...

After showing them a youtube video about the problem they saw clearly how the organizer is a sofa and even made a joke about it a few days later.

Relatable math is pretty great. Also really cool is showing how academia translates to enriching our lives in benign ways.

By @jonahx - 5 months
Wow. This solves a problem that's been open for at least 58 years.
By @robinhouston - 5 months
An interesting thing about this proof is that it looks as though an earlier draft relied on computer assistance – see the author’s code repository at https://github.com/jcpaik/sofa-designer – whereas this preprint contains a proof that “does not require computer assistance, except for numerical computations that can be done on a scientific calculator.”
By @parhamn - 5 months
Numberphile had a great video on this a few years ago: https://youtu.be/rXfKWIZQIo4
By @jey - 5 months
Big if true! But has it been reviewed by experts?
By @amai - 5 months
This paper makes use of Mamikons theorem. This theorem is not widely known, but it should be: https://en.m.wikipedia.org/wiki/Visual_calculus
By @nullc - 5 months
So say you have a hallway shaped like a 5, what is the maximum volume 3d-gerver's that can make it through (by being possible to rotate to swap the turning direction?
By @bee_rider - 5 months
Seems like he could have saved himself a whole lot of trouble by just getting a sectional.
By @polygot - 5 months
Pivot!
By @zgs - 5 months
My favourite mathematical problem looks to have been solved.
By @bediger4000 - 5 months
Dies Ikea offer one of these?
By @nephronaut - 5 months
There are more interesting investigations and results This one is ok but not remarkable
By @briandilley - 5 months
What is the practical application of this?