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For containers, __len__ (the special method for determining the length of containers) is used if the explicit Boolean conversion method is not defined. In Ruby, in contrast, only nil (Ruby's null value) and a special false object are false; all else (including the integer 0 and empty arrays) is true.
An undefined variable in the source code of a computer program is a variable that is accessed in the code but has not been declared by that code. [1] In some programming languages, an implicit declaration is provided the first time such a variable is encountered at compile time. In other languages such a usage is considered to be sufficiently ...
The statement is true when either A or B, but not both, are true. This is equivalent to ¬(A ↔ B ... is defined to be another name for ." This is a statement in the ...
The following fallacies involve relations whose truth values are not guaranteed and therefore not guaranteed to yield true conclusions. Types of propositional fallacies: Affirming a disjunct – concluding that one disjunct of a logical disjunction must be false because the other disjunct is true; A or B; A, therefore not B .
In classical logic, with its intended semantics, the truth values are true (denoted by 1 or the verum ⊤), and untrue or false (denoted by 0 or the falsum ⊥); that is, classical logic is a two-valued logic.
Contrast the term primitive notion, which is a core concept not defined in terms of other concepts. Primitive notions are used as building blocks to define other concepts. Contrast also the term undefined behavior in computer science, in which the term indicates that a function may produce or return any result, which may or may not be correct.
Logical negation is an operation on one logical value, typically the value of a proposition, that produces a value of true if its operand is false and a value of false if its operand is true. The truth table for NOT p (also written as ¬p , Np , Fpq , or ~p ) is as follows:
Classical negation is an operation on one logical value, typically the value of a proposition, that produces a value of true when its operand is false, and a value of false when its operand is true. Thus if statement P {\displaystyle P} is true, then ¬ P {\displaystyle \neg P} (pronounced "not P") would then be false; and conversely, if ¬ P ...