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# Topic: Logical operator

###### In the News (Mon 17 Jun 19)

 Logical conjunction - Wikipedia, the free encyclopedia In mathematics, logical conjunction (usual symbol and) is a logical operator that results in true if both of the operands are true. In logic and technical fields that use it, conjunction, or and, is a logical operator in logical calculi, and a rule of inference in deductive systems. Logically, the sentence "it's raining, but the sun is shining" is equivalent to "it's raining, and the sun is shining", so logically, "but" is equivalent to "and". www.wikipedia.org /wiki/Logical_conjunction   (567 words)

 Logical connective - Wikipedia, the free encyclopedia In formal logic, logical connectives, also known as logical connectors and sometimes logical constants, serve to connect statements into more complicated compound statements. Logical operators are implemented as logic gates in digital circuits. The "logical equivalence" of "NAND alone", "NOR alone", and "NOT and AND" is similar to Turing equivalence. en.wikipedia.org /wiki/Logical_operator   (574 words)

 Logical conjunction   (Site not responding. Last check: 2007-11-07) In logic and technical fields that use it conjunction or and is a logical operator in logical calculi and a rule of inference in systems. Logically sentence "it's raining but the sun is is equivalent to "it's raining and the is shining" so logically "but" is equivalent "and". That implication captures the semantic difference "and" and "but" without disturbing their logical On the other hand in Brazilian logic the logical equivalence is broken between A BUT NOT B (where "BUT NOT" is a single and A AND (NOT B) which is a weaker statement. www.freeglossary.com /And_(logic)   (601 words)

 Logical Operators and Short-circuit Control Forms For modular types, the predefined logical operators are defined on a bit-by-bit basis, using the binary representation of the value of the operands to yield a binary representation for the result, where zero represents False and one represents True. The logical operators on arrays are performed on a component-by-component basis on matching components (as for equality -- see 4.5.2), using the predefined logical operator for the component type. For the logical operators on arrays, a check is made that for each component of the left operand there is a matching component of the right operand, and vice versa. www.adaic.org /standards/95lrm/html/RM-4-5-1.html   (354 words)

 Exclusive disjunction article - Exclusive disjunction logic English disjunction logical operator propositions truth - ...   (Site not responding. Last check: 2007-11-07) In logic, the treatment of the word or requires a little care (for a native English speaker; some other languages have greater precision). The xor operation is sometimes used as a simple mixing function in cryptography, for example, with one-time pad or Feistel network systems. In digital logic design, a two-input xor logic gate is often thought of as a programmable inverter, in that if one input is held at a logic '1', the output will be the inverse of the other input. www.what-means.com /encyclopedia/Exclusive_disjunction   (597 words)

 Logical Conjunction   (Site not responding. Last check: 2007-11-07) In logic and technical fields that use it, conjunction, or and, is a logical operator in logical calculi. Conjunction as we've described it is a binary operator, meaning that it combines two terms into a single statement. The analogue of conjunction for a (possibly infinite) familiy of statements is universal quantification, which is part of predicate logic. www.wikiverse.org /logical-conjunction   (547 words)

 System and method for text searching using an n-ary search tree - Patent 5412807 The PHRASE logical operator is similar to the AND logical operator except that it relates to sequences of multiple word terms which must appear in the specified sequence and must occur one word term apart. The logic unit constructs an n-ary Boolean search tree with a root node representing the results of a text search where terminal nodes contain word terms representing the various user-selected portions and the non-terminal nodes contain logical operator terms representing the user-specified conditions that interrelate the word terms. Logical operator terms, which are contained in non-terminal nodes, interrelate the word terms contained in the terminal nodes that are adjacent to the non-terminal nodes. www.freepatentsonline.com /5412807.html   (9425 words)

 DB Optim TPC-D Model: Concept The query tree shown in figure 3.2a is obtained from the memo structure shown in figure 3.3 by choosing the third logical expression in group 4, which uses groups 0 and 6 as inputs, and the second logical expression in group 6. The query tree shown in figure 3.2b is obtained from the memo structure shown in figure 3.3 by choosing the sixth logical expression in group 4, which uses groups 2 and 3 as inputs, and the second logical expression in group 2. Item operators are distinguished from bulk operators (the logical and physical operators) in that they operate on a fixed number (usually one) of tuples, while bulk operators operate on an arbitrary number of tuples. www.cs.pdx.edu /~kgb/t/pages/fc0.shtml   (6645 words)

 Glossary - Logical Operators   (Site not responding. Last check: 2007-11-07) Logical operators are generally derived from Boolean algebra, which is a mathematical way of manipulating the truth values of concepts in an abstract way without bothering about what the concepts actually mean. As with other image arithmetic operations, it is also possible to logically combine a single input image with a constant logical value, in which case each pixel in the input image is compared to the same constant in order to produce the corresponding output pixel. Logical operations can also be carried out on images with integer pixel values. www.dai.ed.ac.uk /HIPR2/logic.htm   (511 words)

 PHP: Operators - Manual (the negation operator) or ++ (the increment operator). Operators on the same line have equal precedence, in which case their associativity decides which order to evaluate them in. The table also omits the precedence (and associativity) of the "execution operator" - but since that's a sort of quoting, I don't think it meaningfully has a precedence or associativity - they explain what is to happen where there's an open-endedness in the sense of missing brackets, and the quoting is a sort of bracket. www.php.net /manual/en/language.operators.php   (1258 words)

 DB Optim TPC-D Model: l For each logical operator, we show a diagram of the operator's inputs and parameters, an example use of an operator, a description of how the logical properties of the output are computed and the values of the output's logical properties for the given example. This calculation is based on the logical properties of the input(s) and the logical operator itself. When there is only one input, and the operator does not affect a logical property, the notation, "same" indicates that the value of the logical property for the input is copied to this logical property for the output. www.cs.pdx.edu /~kgb/t/pages/l0.shtml   (1725 words)

 PHP: Logical Operators - Manual Utilizing the bitwise operators in a logical context could violates the expectations of the reader and may create confusion because bitwise operators imply bit-field operands. I also feel that assuming that short-circuit evaluation is best for logical constructs IS within the compiler's "rights", since when logical operators are used for their intended purpose, the assumptions that short-circuiting makes *ARE* logical, and do (once again, when used correctly) optimize evaluation of logical expressions. If a non-bitwise operation returns null (in other words, the value being assigned turns out to be null or 0), the bitwise operator would bind to that (or more appropriately, would "see" it) as a "0", otherwise it would see a non-zero (string of bits with at least one "1" in it). www.php.net /manual/en/language.operators.logical.php   (1909 words)

 logical operator concept from the Java knowledge base   (Site not responding. Last check: 2007-11-07) logical operator concept from the Java knowledge base syntactic unit > symbol > operator > logical operator is evaluated before another operator with lower precedence www.csi.uottawa.ca:4321 /java/logicaloperator.html   (44 words)

 Logical operator   (Site not responding. Last check: 2007-11-07) In logical calculus, logical operatorsor logical connectors serve to connect statements into more complicated compound statements. So for example, P ∨ Q ∧ ¬ R → S is shortfor (P ∨ (Q ∧ (¬ R)) → S. Note that the logical equivalence of certain compoundstatements entails that not all of these operators are necessary for a full-blooded logical calculus. For example, ¬ P ∨ Qis logically equivalent to P → Q; since logical equivalence means that equivalent terms may be subsituted for each other inan expression, it's not necessary to have a conditional operator. www.therfcc.org /logical-operator-48934.html   (349 words)

 Propositional Logic [Internet Encyclopedia of Philosophy] In propositional logic, the simplest statements are considered as indivisible units, and hence, propositional logic does not study those logical properties and relations that depend upon parts of statements that are not themselves statements on their own, such as the subject and predicate of a statement. However, there are other forms of propositional logic in which other truth-values are considered, or in which there is consideration of connectives that are used to produce statements whose truth-values depend not simply on the truth-values of the parts, but additional things such as their necessity, possibility or relatedness to one another. A logical operator is said to be truth-functional if the truth-values (the truth or falsity, etc.) of the statements it is used to construct always depend entirely on the truth or falsity of the statements from which they are constructed. www.iep.utm.edu /p/prop-log.htm   (8796 words)

 Logical operator   (Site not responding. Last check: 2007-11-07) In logical calculus logical operators or logical connectors serve to connect statements into more compound statements. The basic operators are " not " (¬ or ~) " and " (∧ $\landor and\right) " or " \left(\vee \right) " conditional " \left(\to \right) and " biconditional " \left(↔\right).$ So for example ∨ Q ∧ ¬ R → S short for (P ∨ (Q ∧ (¬ → S. Note that the logical equivalence of certain compound statements entails that all of these operators are necessary for full-blooded logical calculus. www.freeglossary.com /Connective   (542 words)

 Day 4 -- More Operators   (Site not responding. Last check: 2007-11-07) When the logical OR operator is used in a larger expression, its value is the last subexpression actually evaluated, which is the first subexpression of the logical OR operator that is nonzero. operator is in front of the variable, the operation is a pre-decrement operation, which means that 1 is subtracted from the variable before anything else happens. operator is when two operations are so closely tied together that it is easier to understand the program if they appear as part of the same expression. cdt.www1.50megs.com /tutorial/perl/ch4.htm   (7074 words)

 Logical conjunction - Encyclopedia.WorldSearch   (Site not responding. Last check: 2007-11-07) Logical conjunction (usual symbol and) is a logical operator that results in true if both of the operands are true. As a rule of inference Conjunction is a valid, simple argument form: Logical conunction is often used for bitwise operations. encyclopedia.worldsearch.com /and.htm   (527 words)

 Logical Operations and Truth Tables It turns out that in order to reliably and objectively construct valid arguments, the logical operations which one uses must be clearly defined and must obey a set of consistent properties. The XOR (eXclusive OR) operator is a binary operator, and is not independent of the operators we have presented thus far (many texts do not introduce it as a separate logical operator). The implication operator (IMPLIES) is a binary operator, and is defined in a somewhat counterintuitive manner (until you appreciate it, that is!). www.rwc.uc.edu /koehler/comath/21.html   (1501 words)

 Sheffer Stroke   (Site not responding. Last check: 2007-11-07) It is named for Henry M. Sheffer, who proved that all the usual operators of logical calculus (not, and, or, implies) could be expressed in terms of it: In complicated logical expressions, normally in terms of other logic functions such as AND and OR, writing these in terms of NAND allows for cheaper construction. There is another logical operator which is able to express all the others: NOR. www.wikiverse.org /sheffer-stroke   (332 words)

 Gnus Manual: Advanced Scoring Syntax These lists may consist of three logical operators, one redirection operator, and various match operators. There is an indirection operator that will make its arguments apply to the ancestors of the current article being scored. Match operators are header name strings followed by a match and a match type. www.gnus.org /manual/gnus_255.html   (214 words)

 Logical OR Operator   (Site not responding. Last check: 2007-11-07) The result of the logical OR operator is 1 if either arguments are logical TRUE and it is 0 if both of its arguments are logical FALSE Put this another way, the result of the logical OR operator is 1 if either argument is not 0 and it is 0 if both of its arguments are 0 This means that as soon as the result is known, the remainder of the expression is ignored. xcprod.com /titan/XCSB-DOC/logical_or.html   (301 words)

 Logical Operators The And operator also performs a bit-wise comparison of identically positioned bits in two numeric expressions and sets the corresponding bit in the result. The XOr operator also performs a bit-wise comparison of identically positioned bits in two numeric expressions and sets the corresponding bit in the result. The Not operator also performs a bit-wise reversal of bits in and sets the corresponding bit in the result. www.oopic.com /and.htm   (229 words)

 Javascript Tip   (Site not responding. Last check: 2007-11-07) The rule is to invert each logical term and invert each logical operator. Sometimes a logical term is more complex than a simple boolean variable. De Morgan's rule is to invert each logical term and invert each logical operator. www.cross-browser.com /talk/demorgan.html   (323 words)

 Using the || Logical Operator   (Site not responding. Last check: 2007-11-07) Perl provides a special logical operator that is ideal for testing the return values from functions. operator will evaluate only the right operand if the left operand is false. Using the comma operator to execute two statements instead of one is awkward and prone to misinterpretation when other programmers look at the script. guides.oernii.sk /practical_perl/node110.html   (201 words)

 Logical Operator NOT   (Site not responding. Last check: 2007-11-07) The logical operator NOT allows the user to express conditions that are best expressed in a negative way. In essence, it reverses the logical value of a condition on which it operates. NOT is typically used with logical operators such as IN, BETWEEN, LIKE, etc., which will be covered in a later section. www.thunderstone.com /site/texisman/node45.html   (260 words)

 dBforums - Logical operators The tutorial you gave me a link to just mentions that there is support for the bitwise XOR operator not the logical XOR operator. Ok, logic operators are either value operations or bitwise operations. Bitwise operations consider the individual bits separately unlike the value operations that treat the while value as an entity. www.dbforums.com /printthread.php?t=998777   (146 words)

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