Second-order may refer to:
Mathematics
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Second order approximation, an approximation that includes quadratic terms
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Second-order arithmetic
In mathematical logic, second-order arithmetic is a collection of axiomatic systems that formalize the natural numbers and their subsets. It is an alternative to axiomatic set theory as a foundation for much, but not all, of mathematics.
A precu ...
, an axiomatization allowing quantification of sets of numbers
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Second-order differential equation, a differential equation in which the highest derivative is the second
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Second-order logic
In logic and mathematics, second-order logic is an extension of first-order logic, which itself is an extension of propositional logic. Second-order logic is in turn extended by higher-order logic and type theory.
First-order logic quantifies ...
, an extension of predicate logic
* Second-order perturbation, in
perturbation theory
In mathematics and applied mathematics, perturbation theory comprises methods for finding an approximate solution to a problem, by starting from the exact solution of a related, simpler problem. A critical feature of the technique is a middl ...
Science and technology
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Second-order cybernetics
Second-order cybernetics, also known as the cybernetics of cybernetics, is the recursive application of cybernetics to itself and the reflexive practice of cybernetics according to such a critique. It is cybernetics where "the role of the observer ...
, the recursive application of cybernetics to itself and the reflexive practice of cybernetics according to this critique.
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Second-order fluid, an extension of fluid dynamics
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Second order Fresnel lens, a size of lighthouse lens
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Second-order reaction, a reaction in which the rate is proportional to the square of a reactant's concentration
Psychology and philosophy
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Second-order conditioning, a form of learning from previous learning
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Second-order desire, the desire to have a desire for something
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Second-order stimulus, a visual stimulus distinguished by an aspect other than luminance
Other uses
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Second Order (religious), the cloistered nuns who are affiliated with mendicant orders of friars
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