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In mathematical logic, monadic second-order logic (MSO) is the fragment of second-order logic where the second-order quantification is limited to quantification over sets. [1] It is particularly important in the logic of graphs , because of Courcelle's theorem , which provides algorithms for evaluating monadic second-order formulas over graphs ...
However, we cannot do the same with the predicate. That is, the following expression: ∃P P(b) is not a sentence of first-order logic, but this is a legitimate sentence of second-order logic. Here, P is a predicate variable and is semantically a set of individuals. [1] As a result, second-order logic has greater expressive power than first ...
A set of sentences is called a theory; thus, individual sentences may be called theorems. To properly evaluate the truth (or falsehood) of a sentence, one must make reference to an interpretation of the theory. For first-order theories, interpretations are commonly called structures. Given a structure or interpretation, a sentence will have a ...
There are several variations in the types of logical operation that can be used in these sentences. The first-order logic of graphs concerns sentences in which the variables and predicates concern individual vertices and edges of a graph, while monadic second-order graph logic allows quantification over sets of vertices or edges.
First-order logic—also called predicate logic, predicate calculus, quantificational logic—is a collection of formal systems used in mathematics, philosophy, linguistics, and computer science. First-order logic uses quantified variables over non-logical objects, and allows the use of sentences that contain variables.
The simplest constituents are atomic sentences. A contemporary semantic definition of truth would define truth for the atomic sentences as follows: An atomic sentence F(x 1,...,x n) is true (relative to an assignment of values to the variables x 1, ..., x n)) if the corresponding values of variables bear the relation expressed by the predicate F.
The second three examples are instances of object control, because the object of the control verb is understood as the subject of the subordinate verb. The argument of the matrix predicate that functions as the subject of the embedded predicate is the controller. The controllers are in bold in the examples.
The truth claim arises in each case from the form of the declarative sentence, and when the latter lacks its usual force, e.g., in the mouth of an actor upon the stage, even the sentence "The thought that 5 is a prime number is true" contains only a thought, and indeed the same thought as the simple "5 is a prime number." [1] In 1918, he argued: