منابع مشابه
The Chemistry of Platonic Triangles
Plato’s geometrical theory of what we now call chemistry, set out in the Timaeus, uses triangles, his stoicheia, as the fundamental units with which he constructs his four elements. A paper claiming that these triangles can be divided indefinitely is criticized; the claim of an error here in the commentary by F.M. Cornford is unfounded. Plato’s constructions of the elements are analyzed using s...
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A triple of vertices in a graph is a frustrated triangle if it induces an odd number of edges. We study the set Fn ⊂ [0, n 3 ] of possible number of frustrated triangles f (G) in a graph G on n vertices. We prove that about two thirds of the numbers in [0, n3/2] cannot appear in Fn, and we characterise the graphs G with f (G) ∈ [0, n3/2]. More precisely, our main result is that, for each n ≥...
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We study the computational complexity of binary valued constraint satisfaction problems (VCSP) given by allowing only certain types of costs in every triangle of variable-value assignments to three distinct variables. We show that for several computational problems, including CSP, Max-CSP, finite-valued VCSP, and general-valued VCSP, the only non-trivial tractable classes are the well known max...
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ژورنال
عنوان ژورنال: Science
سال: 2005
ISSN: 0036-8075,1095-9203
DOI: 10.1126/science.308.5725.1088c