Khả năng xảy ra 51% Attack và giải pháp Hashpower của QUARKCHAIN

The most famous attack on PoW consensus is probably double-spending attack — an attacker could arbitrarily revert a block (and thus revert one or more transactions) by secretly mining a longer attacking fork as long as the attacker has more than 51% hashpower of the network. Although 51% hashpower of the network seems to be a strong requirement if the network’s hashpower is decentralized (e.g., Bitcoin never suffers from 51% attack), recently a lot of PoW blockchains have been double-spending attacked: