Memory less system
A system is memoryless if for any $ t\in \mathbb{R} $ only on the input at $ t_0, $
Eg:
Y(t) = X(t) + X(t-1){ memoryless}
Y(t) = X(t)+X(t-1) { with memory}.<pre>/
'''Invertible systems'''
A system is invertible if distinct inputs yield distinct outputs.
Eg:
<pre> Y(t) = 2x(t) + 3
