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单词 Boolean algebra
释义
Boolean algebra

Physics
  • A form of symbolic logic, devised by George Boole (1815–64) in the middle of the 19th century, which provides a mathematical procedure for manipulating logical relationships in symbolic form. For example in Boolean algebra a+b means a or b, while ab means a and b. It makes use of set theory and is extensively used by the designers of computers to enable the bits 0 and 1, as used in the binary notation, to relate to the logical functions the computer needs in carrying out its calculations.


Mathematics
  • A set of elements defined with two binary operations (∨ and ∧), a unary operation (¬) and two elements 0 and 1 which possess the following properties:

    1. (i) Both operations ∨ and ∧ are commutative and associative.

    2. (ii) 0 is an identity for addition and 1 is an identity for multiplication.

    3. (iii) Each operation ∨ and ∧ is distributive over the other.

    4. (iv) a ∨(¬a) = 1 and a ∧(¬a) = 0 for all a.

    For example, a power set ℘(X), where ∨ is union, ∧ is intersection, ¬ is complentation in X, and 0 is the empty set and 1 is X, is a Boolean algebra. Compare Boolean ring; see also Stone space.


Statistics
  • The algebra, developed by Boole, of events (see sample space), unions, intersections and complementary events in a sample space S. For any events A, B, C the following algebraic laws hold:Boolean algebrawhere A′ and B′ are the complementary events of A and B respectively, and φ is the empty set. The last line of the above comprises the de Morgan laws. The penultimate line comprises the distributive laws and the ante-penultimate line comprises the associative laws.


Computer
  • An algebra that is particularly important in computing. Formally it is a complemented distributive lattice. In a Boolean algebra there is a set of elements B that consists of only 0 and 1. Further there will be two dyadic operations, usually denoted by ∧ and ∨ (or by. and +) and called and and or respectively. There is also a monadic operation, denoted here by ′, and known as the complement operation. These operations satisfy a series of laws, given in the table, where x, y, and z denote arbitrary elements of B.

    There are two very common examples of Boolean algebras. The first consists of the set

    B={FALSE,TRUE}
    with the dyadic AND and OR operations replacing ∧ and ∨ respectively, and the NOT operation producing complements. Thus 1 and 0 are just TRUE and FALSE respectively. This idea can be readily extended to the set of all n-tuples
    (x1,x2,,xn)
    where each xi is in B. The AND and OR operations are then extended to operate between corresponding pairs of elements in each n-tuple to produce another n-tuple; the NOT operation negates each item of an n-tuple.

    The second common example of a Boolean algebra is the set of subsets of a given set S, with the operations of intersection and union replacing ∧ and ∨ respectively; set complement fills the role of Boolean algebra complement.

    Boolean algebras, named for George Boole, the 19th-century English mathematician, are fundamental to many aspects of computing—logic design, logic itself, and aspects of algorithm design. See table.

    Boolean algebra

    Boolean algebra. Laws


Electronics and Electrical Engineering
  • An algebra introduced by George Boole in 1854 originally to provide a symbolic method for analysing human logic. Almost a century later it was also found to provide a means for analysing logical machines. An algebra is a collection of sets together with a collection of operations over those sets. A Boolean algebra may be defined as a set K of Boolean values or constants, along with a set P of three operators AND, OR, and NOT, satisfying certain algebraic laws. The set K contains 2n elements, where n is a nonzero integer, and includes two special elements denoted 0 and 1. Thus in the simplest two-valued Boolean algebra, K = {0,1}. This is the basis for all digital logic design, from the simplest logic functions to complex microprocessors and computers. The set of all subsets of a given set (S) also forms a Boolean algebra, with AND, OR, and NOT being represented by the set operations intersection, union, and complement, respectively.

    https://www.allaboutcircuits.com/textbook/digital/chpt-7/introduction-boolean-algebra/ An introduction to Boolean algebra for electronics engineers


Philosophy
  • A Boolean algebra is a system consisting of a set S and two operations, ∩ and ∪ (cap and cup), subject to the following axioms. For all sets a,b,c, that are members of S:

    1. 1 a ∩ (b ∩ c)=(a ∩ b) ∩ c. Also a ∪ (b ∪ c)=(a ∪ b) ∪ c (associativity)

    2. 2 a ∩ b=b ∩ a. Also a ∪ b=b ∪ a (commutativity)

    3. 3 a ∩ (b ∪ c)=(a ∩ b) ∪ (a ∩ c). Also a ∪ (b ∩ c)=(a ∪ b) ∩ (a ∪ c)(distributivity)

    4. 4 There belong to S two elements, 0 and 1, with the propertiesa ∪ 0=a; a ∩ 1=a (identity)

    5. 5 For each set a in S there exists a set a′ with the properties that a ∪ a′=1, a ∩ a′=0 (complementation).

    The propositional calculus can be represented as a Boolean algebra, with ∩ representing &, ∪ representing ∨, and 1 = T, 0 = F. The Boolean operators are then the truth functors, such as &, ∨, and ¬. A Boolean search is a search for things meeting a condition defined with these operators.

    http://www.allaboutcircuits.com/vol_4/chpt_7/index.html An online tutorial on Boolean algebra


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