<logic, inductive logic, probability, arithmentic of probability> the complex event comprising the occurrence of one or the other (or both) of its constituent events. The probability of an alternative occurrence may be calculated by the formula: P(A v B) = P(A) + P(B) - P(A & B). Thus, for example, the chances of getting "heads" at least once in two flips of a coin are equal to the chances of getting "heads" on the first toss (1/2) plus the chances of getting "heads" on the second toss (1/2) minus the chances of getting "heads" both times (1/4), or 3/4. Recommended Reading: Richard Lowry, The Architecture of Chance: An Introduction to the Logic and Arithmetic of Probability (Oxford, 1989); Ian Hacking, An Introduction to Probability and Inductive Logic (Cambridge, 2001); Donald Gillies, Philosophical Theories of Probability (Routledge, 2000).
[A Dictionary of Philosophical Terms and Names]
Try this search on OneLook / Google