P-complete

Min-plus Circuit Value Problem (MinPlusCVP)

Input

An encoding $\overline{\alpha}$ of a $(\min, +)$ circuit $\alpha$ and rational inputs $x_1, \ldots, x_n$.

Problem

Does $\alpha$ on input $x_1, \ldots, x_n$ output a nonzero value?

Definitions

See ArithCVP.

Status

$\P$-complete (Greenlaw, Hoover and Ruzzo [1]).

Remarks

The reduction to show hardness is from MCVP and works in any ordered semi-group with additive identity $0$ and an element $1$ such that $1 + 1 \geq 1 > 0$. If there is a nonzero element $1$ such that $1 + 1 = 0$ (e.g. in $\Z_2$), then a reduction from NANDCVP exists. In a well-ordered semigroup where $0$ is the minimum element, one or the other of these cases holds. If the semigroup is infinite, the problem may not be in $\P$.

References

  1. Greenlaw, R., Hoover, H. J., and Ruzzo, W. L. (1995). Limits to Parallel Computation: P-Completeness Theory. Oxford University Press. Problem A.1.9.