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Indirect self-reference describes an object referring to itself indirectly. For example, the "this sentence is false." contains a direct self-reference, in which the phrase "this sentence" refers directly to the sentence as a whole. An indirectly self-referential sentence would replace the phrase "this sentence" with an indirect reference; and expression that effectively still referred to the sentence, but did not use the pronoun "this." [1]
Indirect self-reference can be defined rigorously in terms of cycles in a graph of reference relationships. [2]
An example of this is the postcard paradox, in which a sentence refers to another sentence which in turn references the original one. [1]
Indirect self-reference was studied in great depth by W. V. Quine and occupies a central place in the proof of Gödel's incompleteness theorem. [3]
