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In logic, a three-valued logic (also trinary logic, trivalent, ternary, or trilean, sometimes abbreviated 3VL) is any of several many-valued logic systems in which there are three truth values indicating ''true'', ''false'' and some indeterminate third value. This is contrasted with the more commonly known bivalent logics (such as classical sentential or Boolean logic) which provide only for ''true'' and ''false''. Conceptual form and basic ideas were initially created by Jan Łukasiewicz and C. I. Lewis. These were then re-formulated by Grigore Moisil in an axiomatic algebraic form, and also extended to ''n''-valued logics in 1945. ==Representation of values== As with bivalent logic, truth values in ternary logic may be represented numerically using various representations of the ternary numeral system. A few of the more common examples are: * in balanced ternary, each digit has one of 3 values: −1, 0, or +1; these values may also be simplified to −, 0, +, respectively.〔 〕 * in the redundant binary representation, each digit can have a value of -1, 0, 0, or 1 (the value 0 has two different representations) * in the ternary numeral system, each digit is a ''trit'' (trinary digit) having a value of: 0, 1, or 2 * in the skew binary number system, only most-significant non-zero digit has a value 2, and the remaining digits have a value of 0 or 1 * 1 for ''true'', 2 for ''false'', and 0 for ''unknown'', ''unknowable''/''undecidable'', ''irrelevant'', or ''both''.〔 〕 * 0 for ''false'', 1 for ''true'', and a third non-integer "maybe" symbol such as ?, #, ½,〔 〕 or xy. Inside a ternary computer, ternary values are represented by ternary signals. This article mainly illustrates a system of ternary propositional logic using the truth values , and extends conventional Boolean connectives to a trivalent context. Ternary predicate logics exist as well; these may have readings of the quantifier different from classical (binary) predicate logic, and may include alternative quantifiers as well. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Three-valued logic」の詳細全文を読む スポンサード リンク
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