Non-self

Signs are inherent in the various aspects of the immune system which differentiate self from non-self.

For the artificial immune system, the recognition of the non-selfs is classified into two types according to the difference among the non-selfs, and the two approaches for recognizing the non-selfs are inspired from the innate immunity and the adaptive immunity in the biological immune system.

[W]e could at least begin to answer the question, What is self? by referring to some paradigm cases of selves . . . and some paradigm case of non-selves.