Abstract: An event transition model for producing test data may be generated from a plurality of event records, each event record including an event time of an instance, wherein the event transition model includes a plurality of states, each state corresponding to one or more instances of the plurality of event records, event transition probabilities between states, and event transition interval times between states.

Abstract: Provided is a method for storing at least a portion of data registered in a blockchain in each of a plurality of node apparatuses, including selection of selecting whether to store data included in a block in one node apparatus among the plurality of node apparatuses, according to a characteristic of the one node apparatus; and data storage of storing at least a portion of the data included in the block in the one node apparatus, according to a result of the selection.

Abstract: A blockchain processing method and system for verification of deleted data for blockchains. An item of data is deleted from a block of a blockchain by: identifying the block of the blockchain storing the item of data; deleting the item of data from the identified block without deleting a hash value associated with the deleted item of data from the identified block; and adding metadata to a new block of the blockchain identifying the deleted item of data. The metadata includes a block identifier (ID) of the identified block as a location of the deleted item of data as well as the hash value associated with the deleted item of data. The block ID may comprise a root hash in a block header of the identified block, a universally unique identifier (UUID) allocated to the identified block, or an offset from the new block to the identified block.