“conjunction”的概念、定义、翻译、参考文献-科学参考

conjunction

Physics

The alignment of two celestial bodies within the solar system so that they have the same longitude as seen from the earth. A planet that orbits between the sun and the earth (Venus and Mercury) is in superior conjunction when it is in line with the sun and the earth but on the opposite side of the sun to the earth. It is in inferior conjunction when it lies between the earth and the sun. Conjunction may also occur between two planets or a moon and a planet. Compare opposition.

Mathematics

If p and q are statements, then the statement ‘p and q’, denoted by p ∧ q, is the conjunction of p and q. For example, if p is ‘It is raining’ and q is ‘It is Monday’, then p ∧ q is ‘It is raining and it is Monday’. The conjunction of p and q is true only when p and q are both true, and so the truth table is as follows:

Astronomy

The occasion when two Solar System bodies have the same celestial longitude as seen from Earth; the bodies may be a planet and the Sun, two planets, or the Moon and a planet. Superior planets (i.e. those with orbits outside that of the Earth) are at conjunction when they lie directly behind the Sun as seen from Earth. Mercury and Venus, which are closer to the Sun, have two conjunctions; inferior conjunction, when they lie between the Earth and Sun; and superior conjunction, when they lie on the far side of the Sun.

Computer

A logical expression of the form
$a_{1} \land a_{2} \land \dots \land a_{n}$
where ∧ is the AND operation. A particular conjunction of interest is the conjunctive normal form (CNF) of a Boolean expression involving n variables, x₁, x₂,…, x_n. Each a_i is of the form
$(y_{1} \lor y_{2} \lor \dots \lor y_{n})$
where ∨ is the OR operation and y_i is equal to x_i or the complement of x_i. Reducing expressions to conjunctive normal form provides a ready method of determining the equivalence of two Boolean expressions. See also propositional calculus. Compare disjunction.

Logic

A binary connective whose truth conditions are taken to mirror the central aspects of the natural language use of the word ‘and’. For example, in many semantic presentations of a conjunction $\land$ , a condition like the following is included:
- • $φ \land ψ$ is true if and only if $φ$ is true and $ψ$ is true.
While rare, there are some non-classical connectives sometimes construed as conjunction for which the above does not exhaust their truth conditions. For example, the binary connective $\circ$ of fusion—often encountered in relevant logics—has an interpretation as an intensional type of conjunction, in which $φ \circ ψ$ is read as ‘ $φ$ and $ψ$ are mutually compatible’ or ‘ $φ$ and $ψ$ are compossible’.

Philosophy

The conjunction of two propositions, p, q, is the proposition p & q. It is true if, and only if, each of p, q is true. The medievals were interested in whether there exist different kinds of conjunction subject to a weaker condition, since while a book is a conjunction of the assertions it contains, it seems harsh to say that it is wholly false if one of them is false. See also truth function.

单词	conjunction
释义	conjunction Physics The alignment of two celestial bodies within the solar system so that they have the same longitude as seen from the earth. A planet that orbits between the sun and the earth (Venus and Mercury) is in superior conjunction when it is in line with the sun and the earth but on the opposite side of the sun to the earth. It is in inferior conjunction when it lies between the earth and the sun. Conjunction may also occur between two planets or a moon and a planet. Compare opposition. Mathematics If p and q are statements, then the statement ‘p and q’, denoted by p ∧ q, is the conjunction of p and q. For example, if p is ‘It is raining’ and q is ‘It is Monday’, then p ∧ q is ‘It is raining and it is Monday’. The conjunction of p and q is true only when p and q are both true, and so the truth table is as follows: Astronomy The occasion when two Solar System bodies have the same celestial longitude as seen from Earth; the bodies may be a planet and the Sun, two planets, or the Moon and a planet. Superior planets (i.e. those with orbits outside that of the Earth) are at conjunction when they lie directly behind the Sun as seen from Earth. Mercury and Venus, which are closer to the Sun, have two conjunctions; inferior conjunction, when they lie between the Earth and Sun; and superior conjunction, when they lie on the far side of the Sun. Computer A logical expression of the form $a_{1} \land a_{2} \land \dots \land a_{n}$ where ∧ is the AND operation. A particular conjunction of interest is the conjunctive normal form (CNF) of a Boolean expression involving n variables, x₁, x₂,…, x_n. Each a_i is of the form $(y_{1} \lor y_{2} \lor \dots \lor y_{n})$ where ∨ is the OR operation and y_i is equal to x_i or the complement of x_i. Reducing expressions to conjunctive normal form provides a ready method of determining the equivalence of two Boolean expressions. See also propositional calculus. Compare disjunction. Logic A binary connective whose truth conditions are taken to mirror the central aspects of the natural language use of the word ‘and’. For example, in many semantic presentations of a conjunction $\land$ , a condition like the following is included: • $φ \land ψ$ is true if and only if $φ$ is true and $ψ$ is true. While rare, there are some non-classical connectives sometimes construed as conjunction for which the above does not exhaust their truth conditions. For example, the binary connective $\circ$ of fusion—often encountered in relevant logics—has an interpretation as an intensional type of conjunction, in which $φ \circ ψ$ is read as ‘ $φ$ and $ψ$ are mutually compatible’ or ‘ $φ$ and $ψ$ are compossible’. Philosophy The conjunction of two propositions, p, q, is the proposition p & q. It is true if, and only if, each of p, q is true. The medievals were interested in whether there exist different kinds of conjunction subject to a weaker condition, since while a book is a conjunction of the assertions it contains, it seems harsh to say that it is wholly false if one of them is false. See also truth function.
随便看	sign on sign stimulus sign/symbol sign test signum function SIG quote Sihanouk, Norodom (1922–2012) Sikhism Sikhote–Alin meteorite Sikh Wars (1845–49) Sikorski, Władysław (1881–1943) SIL silane silcrete SIL devices silent discharge silent mutation silent quake silent zone Silesian silex silica silica gel silicane silica-oversaturated rock