Mutual exclusivity - wikipedia Mutual exclusivity This article is about logical exclusivity of events and propositions. For the concept in concurrent computing, see Mutual exclusion. For the concept in developmental psychology, see Mutual exclusivity ( psychology ). This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. Please help to improve this article by introducing more precise citations. ( October 2009 ) In logic and probability theory, two events ( or propositions ) are mutually exclusive or disjoint if they can not both occur at the same time ( be true ). A clear example is the set of outcomes of a single coin toss, which can result in either heads or tails, but not both. In the coin - tossing example, both outcomes are, in theory, collectively exhaustive, which means that at least one of the outcomes must happen, so these two possibilities together exhaust all the possibilities. However, not all mutually exclusive events are collectively exhaustive. For example, the outcomes 1 and 4 of a single roll of a six - sided die are mutually exclusive ( both can not happen at the same time ) but not collectively exhaustive ( there are other possible outcomes ; 2, 3, 5, 6 ). Contents 1 Logic 2 Probability 3 Statistics 4 See also 5 Notes 6 References Logic In logic, two mutually exclusive propositions are propositions that logically can not be true in the same sense at the same time. To say that more than two propositions are mutually exclusive, depending on context, means that one can not be true if the other one is true, or at least one of them can not be true. The term pairwise mutually exclusive always means that two of them can not be true simultaneously. Probability In probability theory, events E, E,..., E are said to be mutually exclusive if the occurrence of any one of them implies the non-occurrence of the remaining n − 1 events. Therefore, two mutually exclusive events can not both occur. Formally said, the intersection of each two of them is empty ( the null event ) : A ∩ B = ∅. In consequence, mutually exclusive events have the property : P ( A ∩ B) = 0. For example, it is impossible to draw a card that is both red and a club because clubs are always black. If just one card is drawn from the deck, either a red card ( heart or diamond ) or a black card ( club or spade ) will be drawn. When A and B are mutually exclusive, P ( A ∪ B) = P ( A ) + P ( B ). To find the probability of drawing a red card or a club, for example, add together the probability of drawing a red card and the probability of drawing a club. In a standard 52 - card deck, there are twenty - six red cards and thirteen clubs : 26 / 52 + 13 / 52 = 39 / 52 or 3 / 4. One would have to draw at least two cards in order to draw both a red card and a club. The probability of doing so in two draws depends on whether the first card drawn were replaced before the second drawing, since without replacement there is one fewer card after the first card was drawn. The probabilities of the individual events ( red, and club ) are multiplied rather than added. The probability of drawing a red and a club in two drawings without replacement is then 26 / 52 × 13 / 51 × 2 = 676 / 2652, or 13 / 51. With replacement, the probability would be 26 / 52 × 13 / 52 × 2 = 676 / 2704, or 13 / 52. In probability theory, the word or allows for the possibility of both events happening. The probability of one or both events occurring is denoted P ( A ∪ B) and in general it equals P ( A ) + P ( B ) -- P ( A ∩ B). Therefore, in the case of drawing a red card or a king, drawing any of a red king, a red non-king, or a black king is considered a success. In a standard 52 - card deck, there are twenty - six red cards and four kings, two of which are red, so the probability of drawing a red or a king is 26 / 52 + 4 / 52 -- 2 / 52 = 28 / 52. Events are collectively exhaustive if all the possibilities for outcomes are exhausted by those possible events, so at least one of those outcomes must occur. The probability that at least one of the events will occur is equal to one. For example, there are theoretically only two possibilities for flipping a coin. Flipping a head and flipping a tail are collectively exhaustive events, and there is a probability of one of flipping either a head or a tail. Events can be both mutually exclusive and collectively exhaustive. In the case of flipping a coin, flipping a head and flipping a tail are also mutually exclusive events. Both outcomes can not occur for a single trial ( i.e., when a coin is flipped only once ). The probability of flipping a head and the probability of flipping a tail can be added to yield a probability of 1 : 1 / 2 + 1 / 2 = 1. Statistics In statistics and regression analysis, an independent variable that can take on only two possible values is called a dummy variable. For example, it may take on the value 0 if an observation is of a male subject or 1 if the observation is of a female subject. The two possible categories associated with the two possible values are mutually exclusive, so that no observation falls into more than one category, and the categories are exhaustive, so that every observation falls into some category. Sometimes there are three or more possible categories, which are pairwise mutually exclusive and are collectively exhaustive -- for example, under 18 years of age, 18 to 64 years of age, and age 65 or above. In this case a set of dummy variables is constructed, each dummy variable having two mutually exclusive and jointly exhaustive categories -- in this example, one dummy variable ( called D ) would equal 1 if age is less than 18, and would equal 0 otherwise ; a second dummy variable ( called D ) would equal 1 if age is in the range 18 - 64, and 0 otherwise. In this set - up, the dummy variable pairs ( D, D ) can have the values ( 1, 0 ) ( under 18 ), ( 0, 1 ) ( between 18 and 64 ), or ( 0, 0 ) ( 65 or older ) ( but not ( 1, 1 ), which would nonsensically imply that an observed subject is both under 18 and between 18 and 64 ). Then the dummy variables can be included as independent ( explanatory ) variables in a regression. Note that the number of dummy variables is always one less than the number of categories : with the two categories male and female there is a single dummy variable to distinguish them, while with the three age categories two dummy variables are needed to distinguish them. Such qualitative data can also be used for dependent variables. For example, a researcher might want to predict whether someone goes to college or not, using family income, a gender dummy variable, and so forth as explanatory variables. Here the variable to be explained is a dummy variable that equals 0 if the observed subject does not go to college and equals 1 if the subject does go to college. In such a situation, ordinary least squares ( the basic regression technique ) is widely seen as inadequate ; instead probit regression or logistic regression is used. Further, sometimes there are three or more categories for the dependent variable -- for example, no college, community college, and four - year college. In this case, the multinomial probit or multinomial logit technique is used. See also Contrariety Dichotomy Disjoint sets Double bind Event structure Oxymoron Synchronicity Notes Jump up ^ Miller, Scott ; Childers, Donald ( 2012 ). Probability and Random Processes ( Second ed. ). Academic Press. p. 8. ISBN 978 - 0 - 12 - 386981 - 4. The sample space is the collection or set of ' all possible ' distinct ( collectively exhaustive and mutually exclusive ) outcomes of an experiment. Jump up ^ intmath.com ; Mutually Exclusive Events. Interactive Mathematics. December 28, 2008. ^ Jump up to : Stats : Probability Rules. ^ Jump up to : Scott Bierman. A Probability Primer. Carleton College. Pages 3 - 4. Jump up ^ Non-Mutually Exclusive Outcomes. CliffsNotes. References Whitlock, Michael C. ; Schluter, Dolph ( 2008 ). The Analysis of Biological Data. Roberts and Co. ISBN 978 - 0 - 9815194 - 0 - 1. Lind, Douglas A. ; Marchal, William G. ; Wathen, Samuel A. ( 2003 ). Basic Statistics for Business & Economics ( 4th ed. ). Boston : McGraw - Hill. ISBN 0 - 07 - 247104 - 2. Philosophy Branches Traditional Metaphysics Ontology Epistemology Logic Ethics Aesthetics Philosophy of Action Art Culture Design Music Film Business Color Cosmos Dialogue Education Environment Futility Happiness Healthcare History Human nature Humor Feminism Language Life Literature Mathematics Mind Pain Psychology Philosophy of psychiatry Philosophy of perception Philosophy Religion Science Physics Chemistry Biology Geography Sexuality Social science Culture Economics Justice Law Politics Society Space and time Sport Technology Artificial intelligence Computer science Engineering Information War Schools of thought By era Ancient Western Medieval Renaissance Early modern Modern Contemporary Ancient Chinese Agriculturalism Confucianism Legalism Logicians Mohism Chinese naturalism Neotaoism Taoism Yangism Zen Greco - Roman Aristotelianism Atomism Cynicism Cyrenaics Eleatics Eretrian school Epicureanism Hermeneutics Ionian Ephesian Milesian Megarian school Neoplatonism Peripatetic Platonism Pluralism Presocratic Pyrrhonism Pythagoreanism Neopythagoreanism Sophistic Stoicism Indian Samkhya Nyaya Vaisheshika Yoga Mīmāṃsā Ājīvika Ajñana Cārvāka Jain Anekantavada Syādvāda Buddhist Śūnyatā Madhyamaka Yogacara Sautrāntika Svatantrika Persian Mazdakism Zoroastrianism Zurvanism Medieval European Christian philosophy Scholasticism Thomism Renaissance humanism East Asian Korean Confucianism Edo Neo-Confucianism Neo-Confucianism Indian Vedanta Acintya bheda abheda Advaita Bhedabheda Dvaita Dvaitadvaita Shuddhadvaita Vishishtadvaita Navya - Nyāya Islamic Averroism Avicennism Illuminationism ʿIlm al - Kalām Sufi Jewish Judeo - Islamic Modern People Cartesianism Kantianism Neo-Kantianism Hegelianism Marxism Spinozism 0 Anarchism Classical Realism Liberalism Collectivism Conservatism Determinism Dualism Empiricism Existentialism Foundationalism Historicism Holism Humanism Anti - Idealism Absolute British German Objective Subjective Transcendental Individualism Kokugaku Materialism Modernism Monism Naturalism Natural law Nihilism New Confucianism Neo-scholasticism Pragmatism Phenomenology Positivism Reductionism Rationalism Social contract Socialism Transcendentalism Utilitarianism Contemporary Analytic Applied ethics Analytic feminism Analytical Marxism Communitarianism Consequentialism Critical rationalism Experimental philosophy Falsificationism Foundationalism / Coherentism Generative linguistics Internalism and Externalism Logical positivism Legal positivism Normative ethics Meta - ethics Moral realism Neo-Aristotelian Quinean naturalism Ordinary language philosophy Postanalytic philosophy Quietism Rawlsian Reformed epistemology Systemics Scientism Scientific realism Scientific skepticism Contemporary utilitarianism Vienna Circle Wittgensteinian Continental Critical theory Deconstruction Existentialism Feminist Frankfurt School New Historicism Hermeneutics Neo-Marxism Phenomenology Posthumanism Postmodernism Post-structuralism Social constructionism Structuralism Western Marxism Other Kyoto School Objectivism Russian cosmism more... Positions Aesthetics Formalism Institutionalism Aesthetic response Ethics Consequentialism Deontology Virtue Free will Compatibilism Determinism Hard Incompatibilism Hard Libertarianism Metaphysics Atomism Dualism Monism Naturalism Epistemology Constructivism Empiricism Idealism Particularism Fideism Rationalism / Reasonism Skepticism Solipsism Mind Behaviorism Emergentism Eliminativism Epiphenomenalism Functionalism Objectivism Subjectivism Normativity Absolutism Particularism Relativism Nihilism Skepticism Universalism Ontology Action Event Process Reality Anti-realism Conceptualism Idealism Materialism Naturalism Nominalism Physicalism Realism Philosophy by region Philosophy - related lists Miscellaneous By region African Ethiopian Aztec Native America Eastern Chinese Egyptian Czech Indian Indonesian Iranian Japanese Korean Vietnam Pakistani Western American Australian British Danish French German Greek Italian Polish Romanian Russian Slovene Spanish Turkish Lists Outline Index Years Problems Schools Glossary Philosophers Movements Publications Miscellaneous Women in philosophy Sage ( philosophy ) Portal Book Retrieved from `` https://en.wikipedia.org/w/index.php?title=Mutual_exclusivity&oldid=865696397 '' Categories : Philosophy of mathematics Logic Abstraction Dichotomies Hidden categories : Articles lacking in - text citations from October 2009 All articles lacking in - text citations Talk Contents About Wikipedia Español فارسی Português Română Русский Slovenščina ไทย Українська اردو 中文 3 more Edit links This page was last edited on 25 October 2018, at 15 : 35 ( UTC ). Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia ® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization. About Wikipedia

Question: what does it mean when two events are mutually exclusive
Answer: if they cannot both occur at the same time(be true)