Jain's incidence-code parameter conjecture for unit graphs

Let nn be a natural number, let G(Zn)G(\mathbb{Z}_n) be a unit graph, and let HH be a V×E|V|\times|E| incidence matrix of G(Zn)G(\mathbb{Z}_n). Let ϕ(n)\phi(n) denote Euler's totient function, and let Cq(H)C_q(H) denote the code generated by HH over the finite field Fq\mathbb{F}_q. Jain's incidence-code conjecture. If 2U(Zn)2\in U(\mathbb{Z}_n), then the binary code generated by HH is

C2(H)=[(n1)ϕ(n)2,n1,ϕ(n)1]2C_2(H)=\left[\frac{(n-1)\phi(n)}{2}, n-1, \phi(n)-1\right]_2

over F2\mathbb{F}_2. If 2NU(Zn)2\in N_U(\mathbb{Z}_n), then, for any odd prime qq, the qq-ary code generated by HH is

Cq(H)=[nϕ(n)2,n1,ϕ(n)]qC_q(H)=\left[\frac{n\phi(n)}{2}, n-1, \phi(n)\right]_q

over Fq\mathbb{F}_q.

This conjecture specifies the length, dimension, and minimum distance of incidence-matrix codes associated with unit graphs. The surrounding paper states that it resolves this coding-theoretic conjecture from Jain2023, so this candidate is treated as solved.

Sources & referencesView supporting material

Primary source

Apurba Sarkar, Kalyan Hansda and Makhan Maji, “Linear Codes Derived from the Structure of Unit Graphs Over Z_n”, arXiv:2503.03421 (2025).

Progress summary

Never refreshed

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Solutions 0

No solutions have been posted yet.