Noperthedron

8 Computational Step

Definition 51
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We define rational approximations of the 90 noperthedron vertices by \(\lfloor x \cdot 10^{16} \rfloor /10^{16}\).

Theorem 52
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nopertQ is a \(\kappa \)-rational approximation of the Noperthedron.

Proof ▶
Theorem 53
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There exists a valid solution table whose zeroth row covers

\begin{align*} \theta _1,\theta _2& \in [0,2\pi /15] \subset [0,0.42], \\ \varphi _1& \in [0,\pi ] \subset [0,3.15],\\ \varphi _2& \in [0,\pi /2] \subset [0,1.58],\\ \alpha & \in [-\pi /2,\pi /2] \subset [-1.58,1.58]. \end{align*}
Proof ▶

By exhibiting the table and running the validity checking algorithm. Formalized as Noperthedron.NativeCaseAnalysis.solutionTable in the build-on-demand NativeCaseAnalysis library (checked with native_decide) and independently in the kernel-only KernelCaseAnalysis library (checked with decide +kernel, using only the standard axioms); both are kept out of the default build targets so that CI runs stay fast.

Theorem 54
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If a global node in the solution tree is valid, then there is no Rupert solution for its interval.

Proof ▶
Theorem 55
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If a local node in the solution tree is valid, then there is no Rupert solution for its interval.

Proof ▶

If we have a valid solution table, and in particular its \(i\)th row is valid, then there is no Rupert solution of the interval of its \(i\)th row.

Proof ▶

By strong induction on the number of rows left in the table following the \(i\)th. This is because validity constrains each row to only refer to later entries. For a split row, every point in its interval belongs to a child interval at a larger index, so the induction hypothesis excludes a Rupert solution there. At a leaf, apply Theorem 54 or Theorem 55.

Corollary 57
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If we have a valid solution table, then there is no Rupert solution of the interval of its zeroth row.

Proof ▶

Immediate special case of theorem 56.