- Conditioned disjunction
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In logic, conditioned disjunction (sometimes called conditional disjunction) is a ternary logical connective introduced by Church.[1]. Given operands p, q, and r, which represent truth-valued propositions, the meaning of the conditioned disjunction [p, q, r] is given by:
In words, [p, q, r] is equivalent to: "if q then p, else r", or "p or r, according as q or not q". So, for any values of p, q, and r, the value of [p, q, r] is the value of p when q is true, and is the value of r otherwise.
In conjunction with truth constants denoting each truth-value, conditioned disjunction is truth-functionally complete for classical logic.[2] Its truth table is the following:
Conditioned disjunction p q r [p,q,r] T T T T T T F T T F T T T F F F F T T F F T F F F F T T F F F F There are other truth-functionally complete ternary connectives.
References
- ^ Church, Alonzo (1956). Introduction to Mathematical Logic. Princeton University Press.
- ^ Wesselkamper, T., "A sole sufficient operator", Notre Dame Journal of Formal Logic, Vol. XVI, No. 1 (1975), pp. 86-88.
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