Your definition of causality seems sufficient, but you may want to mention in your definition of non-causal if the outputs are only affected by future inputs or if past and present inputs can affect the output as well. -Ryan Scott
Your definitions of causal and non-causal systems look good to me. -Christen Juzeszyn
Your definitions look good. You may want to consider adding some examples as well. - Joseph Mazzei
Correct and to the point - Ronny Wijaya
These definitions are concise and correct, but adding a few examples or a mathematical definition would help as well. As mentioned above, a non-causal system may depend on future inputs or on future inputs and past and present or both. -Zachary Curosh
Your definition of the causal system is clear and correct. With the right choice of words, you make this concept easy to understand. - Bavorndej Chanyasak
Your definitions seem accurate and easy to understand. I specially like your definition for a non-causal system because you mentioned the fact that a system will still be non-causal if there are past/present inputs affecting the outputs along with a future input.
Vivek Ravi
Looks good to me. But what about the system y(t) = x(sin(t))? I remember seeing that somewhere and I wasn't sure if it was causal or not. - Tyler Johnson
You made a logical mistake in the second defintion: the negation of "for all" is "there exists". --Mboutin 15:15, 19 September 2008 (UTC)
