OpenAI reports a nonspectrahedral hyperbolicity cone

An explicit homogeneous hyperbolic polynomial of degree 20 in 23 real variables has a closed hyperbolicity cone that cannot be represented as the positive-semidefinite region of any finite real symmetric linear matrix pencil in the original variables.

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Understanding the problem

Read the background

An explicit homogeneous hyperbolic polynomial of degree 20 in 23 real variables has a closed hyperbolicity cone that cannot be represented as the positive-semidefinite region of any finite real symmetric linear matrix pencil in the original variables.

Why it matters

If correct, disproves the geometric Generalized Lax conjecture that every hyperbolicity cone is spectrahedral.

What counts as progress

Is every hyperbolicity cone representable by a finite symmetric positive-semidefinite pencil?

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