May someone please explain what the notations in the image means?
In general, for a modulus $q$, what does the $+$ in here $\bmod^+ q$ indicate? What does the $\pm$ in here $\bmod^\pm q$ mean?
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Sign up to join this communityMay someone please explain what the notations in the image means?
In general, for a modulus $q$, what does the $+$ in here $\bmod^+ q$ indicate? What does the $\pm$ in here $\bmod^\pm q$ mean?
From the NIST Post-Quantum Cryptography Round 3 submission for Crystals-Kyber:
Modular reductions. For an even (resp. odd) positive integer α, we define $r' = r\bmod^± α$ to be the unique element $r'$in the range $-\frac{α}{2} < r' \le \frac{α}{2}$ (resp. $-\frac{α-1}{2} \le r' \le \frac{α-1}{2}$) such that $r' = r\bmod α$. For any positive integer α, we define $r' = r\bmod^+ α$ to be the unique element $r'$ in the range $0 ≤ r' < α$ such that $r' = r\bmod α$. When the exact representation is not important, we simply write $r' = r\bmod α$.
It is probably also available elsewhere, but this was my source.