AIP 85 attempts to solve the sybil problem that exists in all (D)PoS systems. This ensures that participants in the network that rely on SPV wallets or the API are secured against attackers swarming the network.

https://github.com/ArkEcosystem/AIPs/blob/master/AIPS/aip-85.md

AIP 22 specifies the blueprint for how ark can utilize it's smart-bridges to create decentralized exchanges with high liquidity. The key feature that allows this to happen is the formula based price discovery mechanism proposed in this AIP which doesn't depend on market makers. https://github.com/ArkEcosystem/AIPs/blob/master/AIPS/aip-22.md

Ark being a DPOS network relies on the value of it's tokens to make 51% attacks prohibitively expensive. As a result it makes sense to convert bridge chains that may prove to be competitors to the Ark token's value in the future into cooperative entities that benefit the Ark chain and as a result the network as a whole. In AIP 23 we define a mechanism to achieve this goal by implementing delegate markets for the entire ecosystem on the main Ark chain. https://github.com/ArkEcosystem/AIPs/blob/master/AIPS/aip-23.md

Until now traditional proof of work networks like bitcoin and ethereum have had an advantage, as compared to proof of stake and delegated proof of stake networks, that miners in these networks can follow the longest chain which resolves forks and guarantees that data that has been committed to the blockchain cannot be changed while still allowing new nodes to sync up without compromising trust. This AIP solves that issue and provides the same functionality in a (D)PoS setting without burning any excessive energy. With this AIP now being public I ask all of you to read it and provide feedback and critique. If this approach works (which I'm confident it will, but still have to be scientifically objective) then there is no more purpose for PoW networks since the only feature they offered that other networks could not is now gone and we can take their place. https://github.com/ArkEcosystem/AIPs/blob/master/AIPS/aip-25.md

Proof of Stake systems and Delegated Proof of stake systems are unable to follow the longest chain valid rule because of the risk of a long range attack. In this article we try to discuss some arpproaches that could be used to mitigate that risk and harden a (D)PoS network against long range attacks. https://github.com/ArkEcosystem/AIPs/blob/master/AIPS/aip-27.md