Ethereum Classic [ETC] proposes to set the limits on DAG, preventing mining difficulties

Ethereum Classic claims that DAG – Directed Acyclic Graph, has become a negative factor in the field of crypto-mining and on a long-term the security will be compromised. Ethereum Classic has put forth the issue on an open forum, ECIP: Ethereum Classic Improvement Proposal. The purpose for the ECIP was to set up restrictions on the size of the DAG and to inhibit its vast and rapid growth.

DAG was originally purposed to provide resistance to ASIC from mining protocols and augment decentralization of mining distributors, generating an unbiased distribution of tokens.

Bitfly reported another 51% attack on Ethereum Classic

Hacker stole 807,260 ETC ($ 5.6 million) in 51% Attack