## disjunction

*n.* the separation of pairs of homologous chromosomes during meiosis or of the chromatids of a chromosome during anaphase of mitosis or meiosis. *Compare* nondisjunction.

## disjunction Quick reference

### The Concise Oxford Dictionary of Mathematics (6 ed.)

...disjunction See exclusive disjunction , inclusive disjunction . The common usage of the term ‘or’ where the compound sentence is true if at least one of the parts is true is inclusive disjunction...

## disjunction Reference library

### Oxford Dictionary of Biochemistry and Molecular Biology (2 ed.)

... the separation of chromosomes at anaphase during nuclear...

## disjunction Quick reference

### A Dictionary of Genetics (8 ed.)

... the moving apart of chromosomes during anaphase of mitotic or meiotic...

## disjunction Quick reference

### A Dictionary of Philosophy (3 ed.)

... The statement that at least one of two propositions is true: it thus corresponds to ‘ p or q ’. Inclusive disjunction allows that both may be true; exclusive disjunction that one but not both is true. In the propositional calculus disjunction is treated as a truth function...

## disjunction Quick reference

### A Dictionary of Biomedicine (2 ed.)

...disjunction The separation of the two members of each pair of homologous chromosomes that occurs during meiotic anaphase. Disjunction mutants arise when chromosomes are partitioned unequally between daughter cells as a result of...

## disjunction Quick reference

### A Dictionary of Plant Sciences (4 ed.)

... The separation of homologous chromosomes at the anaphase stage of mitosis and meiosis , and movement towards the poles of the nuclear spindle...

## disjunction Quick reference

### The Oxford Dictionary of English Grammar (2 ed.)

... Semantics . Choice between two possibilities, or an instance of this, typically signalled by the word or . See disjunctive Compare conjunction ( 2 )...

## disjunction Quick reference

### A Dictionary of Zoology (5 ed.)

... The separation of homologous chromosomes at the anaphase stage of mitosis and meiosis , and movement towards the poles of the nuclear spindle ....

## disjunction Quick reference

### A Dictionary of Logic

... A logical connective representing central features of the natural language ‘or’. Standardly, the formal truth condition for disjunction is: • φ ∨ ψ is true if and only if either φ is true or ψ is true. Connectives described as disjunction are sometimes encountered for which the above truth condition does not hold. For example, the relevant logic connective of fusion —in which φ + ψ is treated as an intensional disjunction—requires not that both φ and ψ are true, but that the negation of φ entails the truth of ψ and that the...

##
disjunction
*n.*
Quick reference

### Concise Medical Dictionary (10 ed.)

... n. the separation of pairs of homologous chromosomes during meiosis or of the chromatids of a chromosome during anaphase of mitosis or meiosis. Compare nondisjunction...

##
disjunction
*n.*
Quick reference

### A Dictionary of Psychology (4 ed.)

... n. 1. The act or process of disconnecting, or the state of being disconnected, especially the separation during meiosis or mitosis of the members of each pair of homologous chromosomes . 2. In logic, two propositions ( 1 ) connected by an operator denoting or to form a single compound proposition, usually written p ∨ q , where p and q represent the component propositions or disjuncts, the compound proposition being true if one or both of its disjuncts are true. Also called an inclusive disjunction to distinguish it from the less...

## disjunction Reference library

*Ruth Barcan Marcus*

### The Oxford Companion to Philosophy (2 ed.)

... . A proposition ( P or Q ), where P and Q are propositions, is a disjunction. In English ‘or’is ambiguous; especially as between an inclusive use, i.e. ( P or Q ) or both) and an exclusive use, i.e. ( P or Q ) and not both). In the propositional calculus , an inclusive disjunction is standardly represented by ( P Δ Q ). It is true except where both P and Q are false. No further relation as between the content of P and Q is required. ( Truth-function .) An exclusive disjunction can be given by ( P Δ Q )·∼( P · Q ). The inference...

## disjunction Quick reference

### A Dictionary of Computer Science (7 ed.)

... A logical expression of the form a 1 ∨ a 2 ∨ … ∨ a n where ∨ is the OR operation . A particular disjunction of interest is the disjunctive normal form of a Boolean expression involving n variables, x 1 , x 2 ,…, x n . Each a i is then of the form ( y 1 ∧ y 2 ∧ … y n ) where ∧ is the AND operation and each y i is equal to x i or the complement of x i . Reducing expressions to disjunctive normal form provides a ready method of determining the equivalence of two Boolean expressions. See also propositional calculus . Compare ...

## disjunction Quick reference

### The Concise Oxford Dictionary of Linguistics (3 ed.)

... Coordination that distinguishes alternatives: e.g. in She will come by bike or she will take a bus . A coordinator such as or is a disjunctive conjunction, a question such as Will you go or will you stay? is a disjunctive question, and so on. A term from logic, where a disjunctive operator (∨) is defined as connecting propositions at least one of which is thereby represented as true. Thus p ∨ q means ‘Either p is true or q is true or both’. Compare conjunction (2)...

## exclusive disjunction Quick reference

### The Concise Oxford Dictionary of Mathematics (6 ed.)

...exclusive disjunction If p and q are statements, then the statement ‘ p or q ’ where exclusive disjunction is intended, often written as ‘ p xor q ’ or p ⊻ q , is true only if exactly one of p , q is true. The truth table is therefore as follows: The set-theoretic equivalent of exclusive disjunction is symmetric difference . See also inclusive disjunction...

## postreductional disjunction Quick reference

### A Dictionary of Genetics (8 ed.)

...disjunction referring to the separation of alleles at particular heterozygous loci during the first meiotic division. If the loci are represented by A and A′ , in the case of postreductional disjunction the two chromatics that enter one sister nucleus have one A and one A′ allele, whereas in the case of prereductional disjunction both have A alleles or both A′ ...

## disjunction property Quick reference

### A Dictionary of Logic

... property 1. For a deductive system L , the property that for every disjunctive L -theorem φ ∨ ψ , either φ is theorem of L or ψ is theorem of L . Most notably, intuitionistic logic enjoys the disjunction property. 2. For a theory T and deductive system L , the property holding of T when T ⊢ L φ ∨ ψ only if T ⊢ φ L or T ⊢ ψ L . The disjunction property is most commonly discussed in the context of intuitionistic logic, e.g. , the intuitionistic Heyting Arithmetic HA enjoys the disjunction...

## disjunction elimination Quick reference

### A Dictionary of Philosophy (3 ed.)

... elimination The rule permitting one to infer from ‘either A or B; if A then C, if B then C; so...

## disjunction introduction Quick reference

### A Dictionary of Philosophy (3 ed.)

... introduction The rule permitting one to infer ‘A so either A or B’ (or equally, B, so either A or...

##
non-disjunction
*n.*
Quick reference

### A Dictionary of Psychology (4 ed.)

...disjunction n . The failure of paired chromosomes to separate and move to opposite poles during mitosis or meiosis ( 1 )...