Literal (mathematical logic)

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In mathematical logic, a literal is an atomic formula (atom) or its negation. Literals can be divided into two types:

• A positive literal is just an atom.
• A negative literal is the negation of an atom.

A pure literal is a literal such that every occurrence of its variable (within some formula) has the same sign.

[edit] References

• Buss, Samuel (1998). "An introduction to proof theory". Handbook of proof theory: 1–78, Elsevier. ISBN 0-444-89840-9.