Theorem · polynomial-time equivalence

FPRD-LRS-T02

Matrix-power equivalence for indexed LRS zeroness

Exact statement

Indexed LRS zeroness is polynomial-time equivalent to deciding whether a specified entry of an integer matrix raised to a binary exponent is zero.

StatusProved by companion, block-matrix, and Cayley–Hamilton constructions
External reviewNo documented external or specialist review of this FPRD result is recorded.

Context

The equivalence identifies the native computational object: exact zeroness of one coordinate of an exponentially long linear orbit.

Definitions

  • Binary matrix-power zeroness supplies an integer matrix, two indices, and a binary exponent.

Hypotheses and scope

  • Matrices and recurrence data are explicit and binary encoded.

Proof or evidence

A companion representation gives g_n=αA^nβ; a two-state block extension makes this one entry of M^{n+2}. Conversely, every entry sequence (M^k)_{s,t} satisfies the characteristic recurrence by Cayley–Hamilton, with polynomial-size initial data.

Verification notes

The block dimensions, exponent shift, characteristic-polynomial signs, and initial-term size were checked.

Limitations

  • The equivalence is about zeroness, not efficient expansion of the integer value.

Open work

Compare deterministic subclasses on the recurrence and matrix-power sides.