121.
Unifier -- from MathWorld
- Weisstein, Eric W.
See also: Unifiable, Unification
122.
Univalent -- from MathWorld
- Weisstein, Eric W.
Capable of taking on exactly one possible value. See also: Bivalent
123.
Universal Form -- from MathWorld
- Weisstein, Eric W.
See: Skolemized Form
124.
Universal Formula -- from MathWorld
- Weisstein, Eric W.
Also called an existential formula.
125.
Universal Predicate -- from MathWorld
- Weisstein, Eric W.
If the property of being an object is expressed by a basic predicate of the system, then such a predicate (if it exists) is called a universal predicate, or universal category.
126.
Universal Property -- from MathWorld
- Weisstein, Eric W.
A property of individuals which is shared by every individual.
127.
Universal Quantifier -- from MathWorld
- Weisstein, Eric W.
The quantifier "for all" (\forall), sometimes also known as the "general quantifier." See also: Existential Quantifier, Exists, For All, Quantifier
128.
Universal Sentence -- from MathWorld
- Weisstein, Eric W.
A sentence dealing with individual constants in which some constant, say a, appears one or more times and which is true for every individual in the domain of individuals to which a belongs. See also: Existential Sentence
129.
Unsatisfiable -- from MathWorld
- Weisstein, Eric W.
A formula whose truth table contains only false in any interpretation is called unsatisfiable. See also: Interpretation, Satisfiable
130.
Validity -- from MathWorld
- Weisstein, Eric W.
The validity of a logical argument refers to whether or not the conclusion follows logically from the premises, i.e., whether it is possible to deduce the conclusion from the premises and the allowable syllogisms of the logical system being used. If it is possible to do so, the argument is said to be valid; otherwise it is invalid. A classical example of a valid argument is the following: All men are mortal. Socrates is a man. Therefore Socrates is mortal. Truth and validity are different...
131.
Vee -- from MathWorld
- Weisstein, Eric W.
The symbol \vee variously means "disjunction" (i.e., OR in logic) or "join" (for a lattice). See also: OR, Wedge
132.
Venn Diagram -- from MathWorld
- Weisstein, Eric W.
A schematic diagram used in logic theory to depict collections of sets and represent their relationships. The Venn diagrams on two and three sets are illustrated above. The order-two diagram (left) consists of two intersecting circles, producing a total of four regions, A, B, A\cap B, and \varnothing (the empty set, represented by none of the regions occupied). Here, A\cap B denotes the intersection of sets A and B. The order-three diagram (right) consists of three symmetrically placed...
133.
de Morgan's Duality Law -- from MathWorld
- Weisstein, Eric W.
For every proposition involving logical addition and multiplication ("or" and "and"), there is a corresponding proposition in which the words "addition" and "multiplication" are interchanged.
