The Mathematical Functions of IOTAIOTA
Construction & Buildings
Asset Lifecycle Management (ALM)
The node chooses two other transactions to approve according to an algorithm. In general, these two transactions may coincide.
The node checks if the two transactions are not conflicting, and does not approve conflicting transactions.
For a node to issue a valid transaction, the node must solve a cryptographic puzzle similar to those in the Bitcoin blockchain. This is achieved by finding a nonce such that the hash of that nonce concatenated with some data from the approved transaction has a particular form. In the case of the Bitcoin protocol, the hash must have at least a predefined number of leading zeros.