# PSPACE hardness of approximating the capacity of Markoff channels with noiseless feedback

## TL;DR

This paper proves that determining the capacity of Markoff channels with noiseless feedback is computationally very hard, specifically PSPACE-hard, indicating significant complexity in such information-theoretic problems.

## Contribution

It establishes the PSPACE-hardness of approximating the capacity of Markoff channels with noiseless feedback, a novel complexity result in information theory.

## Key findings

- Computing capacity of Markoff channels is PSPACE-hard.
- The problem remains hard even with noiseless feedback.
- Complexity results impact understanding of channel capacity computation.

## Abstract

It will be proved that computing the capacity of a Markoff channel with noiseless feedback is PSPACE-hard.