Difference between causality and memorylessness I have found the particular definitions.

Causality means that the output of the system does not depend on future inputs, but only on past input.

Memory-less - does not depend on previous values of either input or output.

I am looking for example of systems which are either non-casual or memoryless but not both.

Also i want to check whether I understand it well.


  $ T(x[n]) = x[n − n_{0}] $
  
  $T(x[n]) = ax[n] + bx[n − 3]$


Are those an examples of non-casual and memory-less systems?
A causal system does not need to know the future in order to compute its output. A memoryless system computes the output only from the current input. A memoryless system is always causal (as it doesn't depend on future input values), but a causal system doesn't need to be memoryless (because it may depend on past input or output values).

The system $$y[n]=x[n]+2x[n+1]$$ is non-causal because it needs to look into the future (by $1$ sample) to compute its output. The system $$y[n]=3\big(x[n]\big)^2$$ is memoryless (and necessarily causal) because it only needs the current input sample $x[n]$ to compute the output.

The systems in your question are both causal and have memory (if $n_0&gt;0$).