Quantum and CircuitsReading edition

Quadratic projection can destroy safety

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Quadratic projection can destroy safety

At \(m=3\), variables are ordered by source labels \(v=1,2,3,4,5,6\). Assignment index \(13\) is read least-significant-bit first:

\[ (x_1,x_2,x_3,x_4,x_5,x_6)=(1,0,1,1,0,0). \]

The active labels have syndrome \(1+3+4=6\), not \(a=7\).

A concrete accepted point for Q 3 that is rejected by P 3. The variable ordering matches the source checker.
A concrete accepted point for \(Q_3\) that is rejected by \(P_3\). The variable ordering matches the source checker.

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The three linear forms evaluate to \(L=(0,1,1)\), so \(P_3=L_1L_2L_3=0\). The quadratic grade has pairs \((1,6)\), \((2,5)\), \((3,4)\), so

\[ Q_3=x_1x_6+x_2x_5+x_3x_4=0+0+1=1. \]

Thus \(Q_3\notin I_{P_3}\): homogeneous extraction does not preserve the positive-support ideal. The whole polynomial is supported on its own accepting set, but its isolated homogeneous components need not be.

The new script checks all 64 inputs here, finds 24 false positives, and confirms that 13 is the first in the stated integer ordering. The frozen \(m=4\) control similarly has 7,616 false positives among its \(2^{14}\) assignments. These are separate finite statements with exact ranges.

Fresh complete \(m=3\) truth-table check; baseline \(m=4\) check was reproduced by the full source verifier. Safety failure is already established by the single valid assignment above.

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Source SHA-256: 488075fae27e7db2e4bcee68c08f93b659a12536c807e5e419d6e8e166317763

Unsupported prose commands stop the build. The mathematical expression sequence is checked against the source, with manuscript macros expanded for display.

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