topic: algebraic specifications in Maude

deadline: 23.11.2020


Card Payment Terminal
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task 1: create algebraic specification of a payment terminal for cards (used in restaurants and shops)
	- state: idle, waiting for the card (to be inserted or attached), waiting for the PIN, confirmation, and so on
	- support both chip cards and contactless (which are just put close to the reader)
	- operations:
		- card validation (not blocked, expiration date)
		- checking account balance (it has to be sufficiently high)
		- updating the account balance after the successful payment
		- retrieving account information from the central database of a respective bank or a card processing organization (VISA, MasterCard)
		- reading user PIN from keyboard (when it is necessary)

task 2: document your solution
	- explain key decisions and high-level design

task 3: prepare some test cases (scenarios, inputs)
	- common sequences of actions with a payment terminal