IOHK | WHY WE ARE BUILDING CARDANO | 06/28/2017    Our preliminary efforts for finding the right authenticated data structure have resulted in a new type of AVL+ Tree jointly developed by Leo Reyzin, IOHK and Waves . More research is required, but it is a foundational advancement that will be included in a later version of Cardano. A distributed mempool could be implemented using Stanford University’s RAMCloud protocol . Experiments will begin in Q3 of 2017 to study its integration into Cardano’s consensus layer. The remaining topics are interconnected and covered by ongoing research. We expect — subject to research results — to include a protocol into Cardano for UIAs during the Basho of CSL release in 2018. Scalability Distributed systems are composed of a set of computers (nodes) agreeing to run a protocol or suite of protocols to accomplish a common goal. This goal could be sharing a file as defined by the BitTorrent protocol or folding a protein using Folding@Home. The most effective protocols gain resources as nodes join the network. A file hosted by BitTorrent, for example, can be downloaded much faster on average if many peers are concurrently downloading it. The speed increases because the peers provide resources while also consuming them. This characteristic is what one typically means when stating a distributed system scales. The challenge with the design of all current cryptocurrencies is that they actually are not designed to be scalable. Blockchains, for example, are usually an append-only linked list of blocks. The security and availability of a blockchain protocol relies upon many nodes possessing a full copy of the blockchain data. Thus, a single byte of data must be replicated among N nodes. Additional nodes do not provide additional resources. This result is the same for transaction processing and the gossiping of messages throughout the system. Adding more nodes to the consensus system does not provide additional transaction processing power. It just means more resources have to be spent to do the same job. More network relaying meaning more nodes have to pass the same messages to keep the whole network in synchronization with the most current block. Given this topology, cryptocurrencies cannot scale to a global network on par with legacy financial systems. In contrast, legacy infrastructure is scalable and has orders of magnitude for more processing and storage power. Adding a specific point, Bitcoin is a very small network relative to its payment peers, yet struggles to manage its current load. WHY WE ARE BUILDING CARDANO  Creative Commons Attribution 4.0 International License Page 13 of 44