2026/07/27 by Akira Sakurai, Taishi Nakai, Kazuyuki Shudo
#cs.CR #cs.GT
When is honest Bitcoin mining rational? This question is central to the incentive design of proof-of-work blockchains. Sapirshtein et al. computationally derived near-tight lower and upper bounds on the incentive-compatibility threshold using a Markov Decision Process. Kiayias et al.'s Blockchain Mining Games instead derived theoretical lower and upper bounds. However, this theoretical approach has two limitations: its model restricts miners to a narrow action space and assumes idealized tie behavior, and its lower and upper bounds are far from tight. We resolve both limitations. We develop a more realistic model with a broader miner action space and asymmetric tie-breaking parameters γ- and γ+. We then propose an algorithm that computes lower and upper bounds on the incentive-compatibility threshold with a maximum error of 9.98006×10-4.