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Science1 publisher2 min readPublished

Twenty-four integer points build a three-holed polyhedron whose eight faces all touch

Ruslan Mizhaev gave integer coordinates to all 24 vertices of an eight-faced polyhedron with three holes, so others can check it. Each face touches all seven others, some along two edges, in a looser version of the Szilassi polyhedron's all-neighbours pattern.

The Scientist · Science desk

Photograph accompanying Twenty-four integer points build a three-holed polyhedron whose eight faces all touch
Photo: newscientist.com

What happened

  • Ruslan Mizhaev, an independent researcher and design engineer, has built a genus-3 polyhedron, a surface with three holes, from eight flat nine-sided faces.
  • The shape has 24 vertices and 36 edges, and three faces meet at every vertex.
  • All 24 vertices now have integer coordinates, published with equations that let others check the faces are flat, the surface closes and nothing self-intersects.
  • Mizhaev first described the underlying structure in 2020, after hitting on the property while experimenting with polyhedral surfaces in CAD software.

Compiled by The ScientistSomething wrong?How this is made

Why it matters

  • capability Because the vertices are whole numbers, anyone can redo the flatness, closure and intersection checks exactly instead of trusting Mizhaev's CAD model.
  • constraint The doubled edges keep the shape out of the stricter class where each pair of faces meets exactly once, so questions about that class stay where they were.
  • exposure Some verification ran through ChatGPT-written Python scripts, so confidence in the construction rests on someone rerunning the checks from the published coordinates.

The published counts pass the first test any claimed polyhedron should face. Vertices minus edges plus faces gives 24 - 36 + 8 = -4 [1]. A closed surface with that Euler characteristic has genus (2 - (-4))/2 = 3 [2]. That means three handles, in the topologist's sense of holes or tunnels through a surface, of which a doughnut has one [4]. The faces and corners agree too. Eight nine-sided faces have 72 sides between them, and each edge borders two faces, so there are 36 edges; 24 vertices with three edges apiece give the same 72 edge-ends [3].

Mizhaev states the defining property plainly. "There are eight flat, polygonal faces, and each is a neighbour of all seven others along an edge," he said [3]. The tetrahedron and the Szilassi polyhedron also have faces that are all neighbours [5]. According to New Scientist, though, some pairs of faces in Mizhaev's design share two edges instead of one [5]. Counting gives the size of that difference. Eight faces form 28 pairs, and 36 edges leave eight more than one per pair [4].

Integer coordinates make the checks exact. Whether the nine corners of each face lie in one plane becomes a question of whole-number arithmetic with a yes-or-no answer and no rounding tolerance to argue about [8]. Accidental intersections are a common problem in shapes like this one, according to New Scientist, and the supplied equations test for them directly [8].

Lars Schewe at the University of Edinburgh was measured about the result. "It's more a small piece that we didn't have before," he said [9]. He said it does not overturn existing conjectures, but "constructing these has always been a difficult task" [10]. There is no reliable way to do it [11]. Writing down equations for where every vertex can sit and how every face must fit can rapidly become practically impossible to solve, Schewe said, so researchers lean on computer searches, geometric intuition and physical models [11][12].

"I can tell you these are the rules," he said. "But when I try to build it and I try to draw it, I can't do it." [14]

Mizhaev used ChatGPT to help with some verification calculations and to write Python scripts for the new version [13]. He says the original shape dates from 2020, before he began using the chatbot [13]. The integer vertices and checking equations can be run again without those scripts [8]. The report does not say whether anyone outside the project has done that yet.

What to watch

  • An independent rerun of the flatness, closure and intersection equations on the 24 integer vertices by mathematicians outside the project.
  • Whether the construction can be adjusted so every pair of faces shares exactly one edge, as in the tetrahedron and Szilassi polyhedron.
  • Whether the CAD-driven approach produces realisations of other face-adjacency patterns that equation-solving has stalled on.
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