Chemistry

• Reduction, part of a reduction-oxidation (redox
  Redox
  Redox reactions describe all chemical reactions in which atoms have their oxidation state changed....
  
  ) reaction where oxygen is being removed from a compound.
  • Reduced gas
    Reduced gas
    A reduced gas is a gas with a low oxidation number , and is usually hydrogen-rich. Strongly reduced gases include methane, ammonia, and hydrogen sulfide.Such gases are strongly associated with the origin of life....
    
    , a gas with a low oxidation number
  • Reducing atmosphere
    Reducing atmosphere
    A reducing atmosphere, also known as a reduction atmosphere, is an atmospheric condition in which oxidation is prevented by removal of oxygen and other oxidising gases or vapours. Usually nitrogen is used or in more extreme conditions hydrogen gas. In that case the atmosphere is reducing...
    
    , an oxygen-poor gaseous environment that inhibits oxidation
  • Ore reduction: see smelting
    Smelting
    Smelting is a form of extractive metallurgy; its main use is to produce a metal from its ore. This includes iron extraction from iron ore, and copper extraction and other base metals from their ores...
    
    

Computing and algorithms

• Reduction (complexity)
  Reduction (complexity)
  In computability theory and computational complexity theory, a reduction is a transformation of one problem into another problem. Depending on the transformation used this can be used to define complexity classes on a set of problems....
  
  , a transformation of one problem into another problem
• Graph reduction
  Graph reduction
  In computer science, graph reduction implements an efficient version of non-strict evaluation, an evaluation strategy where the arguments to a function are not immediately evaluated. This form of non-strict evaluation is also known as lazy evaluation and used in functional programming languages...
  
  , an efficient version of non-strict evaluation
• Strength reduction
  Strength reduction
  Strength reduction is a compiler optimization where expensive operations are replaced with equivalent but less expensive operations. The classic example of strength reduction converts "strong" multiplications inside a loop into "weaker" additions – something that frequently occurs in array...
  
  , a compiler optimization where a function of some systematically changing variable is calculated more efficiently by using previous values of the function
• Reduction (recursion theory)
  Reduction (recursion theory)
  In computability theory, many reducibility relations are studied...
  
  , given sets A and B of natural numbers, is it possible to effectively convert a method for deciding membership in B into a method for deciding membership in A?
• L-reduction
  L-reduction
  In computer science, in particular in the study of approximation algorithms, anL-reduction is a transformation of optimization problems which linearly preserves approximability features...
  
  , a transformation of optimization problems which keeps the approximability features
• Variance reduction
  Variance reduction
  In mathematics, more specifically in the theory of Monte Carlo methods, variance reduction is a procedure used to increase the precision of the estimates that can be obtained for a given number of iterations. Every output random variable from the simulation is associated with a variance which...
  
  , a procedure used to increase the precision of the estimates that can be obtained for a given number of iterations
• Partial order reduction
  Partial order reduction
  In computer science, partial order reduction is a technique for reducing the size of the state-space to be searched by a model checking algorithm...
  
  , a technique for reducing the size of the state-space to be searched by a model checking algorithm
• Bit Rate Reduction
  Bit Rate Reduction
  Bit Rate Reduction, or BRR, also called Bit Rate Reduced, is a name given toan audio compression method used on the SPC700 sound coprocessor used in the SNES. The method is a form of ADPCM....
  
  , an audio compression method
• Reduce (computer algebra system), a general-purpose computer algebra system geared towards applications in physics
• Reduce (higher-order function), in functional programming, a family of higher-order functions that process a data structure in some order and build up a return value
• Reduced instruction set computer
  Reduced instruction set computer
  Reduced instruction set computing, or RISC , is a CPU design strategy based on the insight that simplified instructions can provide higher performance if this simplicity enables much faster execution of each instruction. A computer based on this strategy is a reduced instruction set computer...
  
  , a CPU design philosophy that favors an instruction set reduced both in size and complexity of addressing modes, in order to enable easier implementation, greater instruction level parallelism, and more efficient compilers

Pure mathematics and statistics

• Reduction (mathematics)
  Reduction (mathematics)
  In mathematics, reduction refers to the rewriting of an expression into a simpler form. For example, the process of rewriting a fraction into one with the smallest whole-number denominator possible is called "reducing a fraction"...
  
  , the rewriting of an expression into a simpler form
• Beta reduction, the rewriting of an expression from lambda calculus into a simpler form
• Dimension reduction, the process of reducing the number of random variables under consideration
• Lattice reduction
  Lattice reduction
  In mathematics, the goal of lattice basis reduction is given an integer lattice basis as input, to find a basis with short, nearly orthogonal vectors. This is realized using different algorithms, whose running time is usually at least exponential in the dimension of the lattice.-Nearly...
  
  , given an integer lattice basis as input, to find a basis with short, nearly orthogonal vectors
• Reduction of order
  Reduction of order
  Reduction of order is a technique in mathematics for solving second-order linear ordinary differential equations. It is employed when one solution y_1 is known and a second linearly independent solution y_2 is desired.-An Example:...
  
  , a technique for solving second-order ordinary differential equations
• Relation reduction, the extent to which a given relation is determined by an indexed family or a sequence of other relations, called the relation dataset
• Reduction of the structure group
  Reduction of the structure group
  In mathematics, in particular the theory of principal bundles, one can ask if a G-bundle "comes from" a subgroup H In mathematics, in particular the theory of principal bundles, one can ask if a...
  
  , for a -bundle and a map an -bundle such that the pushout is isomorphic to
• Reduction system, reduction strategy, the application of rewriting systems to eliminate reducible expressions
• Reduced form
  Reduced form
  In statistics, and particularly in econometrics, the reduced form of a system of equations is the result of solving the system for the endogenous variables. This gives the latter as a function of the exogenous variables, if any...
  
  , in statistics, an equation which relates the endogenous variable X to all the available exogenous variables, both those included in the regression of interest (W) and the instruments (Z)
• Reduced ring
  Reduced ring
  In ring theory, a ring R is called a reduced ring if it has no non-zero nilpotent elements. Equivalently, a ring is reduced if it has no non-zero elements with square zero, that is, x2 = 0 implies x = 0...
  
  , a ring with no non-zero nilpotent elements
• Reduced residue system
  Reduced residue system
  Any subset R of the set of integers is called a reduced residue system modulo n if#gcd = 1 for each r contained in R;#R contains φ elements;#no two elements of R are congruent modulo n....
  
  , a set of φ(n) integers such that each integer is relatively prime to n and no two are congruent modulo n
• Reduced product
  Reduced product
  In model theory, a branch of mathematical logic, and in algebra, the reduced product is a construction that generalizes both direct product and ultraproduct....
  
  , a construction that generalizes both direct product and ultraproduct
• Reduced word, in a free group, a word with no adjacent generator-inverse pairs
• Reduced homology
  Reduced homology
  In mathematics, reduced homology is a minor modification made to homology theory in algebraic topology, designed to make a point have all its homology groups zero...
  
  , a minor modification made to homology theory in algebraic topology, designed to make a point have all its homology groups zero
• Reduced row echelon form, a certain reduced row echelon form of a matrix which completely and uniquely determines its row space

Physics

• Dimensional reduction
  Dimensional reduction
  In physics, a theory in D spacetime dimensions can be redefined in a lower number of dimensions d, by taking all the fields to be independent of the location in the extra D − d dimensions....
  
  , the limit of a compactified theory where the size of the compact dimension goes to zero
• Reduction criterion
  Reduction criterion
  In quantum information theory, the reduction criterion is a necessary condition a mixed state must satisfy in order for it to be separable. In other words, the reduction criterion is a separability criterion.-Details:...
  
  , in quantum information theory, a necessary condition a mixed state must satisfy in order for it to be separable
• Reduced properties
  Reduced properties
  In thermodynamics, the reduced properties of a fluid are a set of state variables normalized by the fluid's state properties at its critical point...
  
   of a fluid, defined based on the fluid's critical point:
  • Reduced pressure
  • Reduced temperature
  • Reduced volume
• Reduced mass
  Reduced mass
  Reduced mass is the "effective" inertial mass appearing in the two-body problem of Newtonian mechanics. This is a quantity with the unit of mass, which allows the two-body problem to be solved as if it were a one-body problem. Note however that the mass determining the gravitational force is not...
  
  , the "effective" inertial mass appearing in the two-body problem of Newtonian mechanics

Technology

• Noise reduction
  Noise reduction
  Noise reduction is the process of removing noise from a signal.All recording devices, both analogue or digital, have traits which make them susceptible to noise...
  
  , acoustic or signal processing
• Reduction drive
  Reduction drive
  A reduction drive is a mechanical device to shift rotational speed. A planetary reduction drive is a small-scale version using ball bearings in an epicyclic arrangement instead of toothed gears....
  
  , a mechanical device to shift rotational speed

Philosophy

• Reduction (philosophy)
  Reduction (philosophy)
  In philosophy, reduction is the process by which one object, property, concept, theory, etc., is shown to be explicable in terms of another, lower level, entity...
  
  , the process by which one object, property, concept, theory, etc., is shown to be entirely dispensable in favor of another
• Intertheoretic reduction
  Intertheoretic reduction
  In philosophy of science, intertheoretic reduction occurs when one theory makes predictions that perfectly or almost perfectly match the predictions of a second theory. Newtonian mechanics, for example, can be reduced to general relativity for velocities far less than c....
  
  , in philosophy of science, one theory makes predictions that perfectly or almost perfectly match the predictions of a second theory
• Eidetic reduction
  Eidetic reduction
  Eidetic reduction is a technique in the study of essences in phenomenology whose goal is to identify the basic components of phenomena. Eidetic reduction requires that a phenomenologist examine the essence of a mental object, be it a simple mental act, or the unity of consciousness itself, with the...
  
  , a technique in the study of essences in phenomenology whose goal is to identify the basic components of phenomena

Medicine

• Weight loss
  Weight loss
  Weight loss, in the context of medicine, health or physical fitness, is a reduction of the total body mass, due to a mean loss of fluid, body fat or adipose tissue and/or lean mass, namely bone mineral deposits, muscle, tendon and other connective tissue...
  
  
• Selective reduction
  Selective reduction
  Selective reduction is the practice of aborting one or more fetuses in a multifetal pregnancy. Such an abortion procedure is often performed after a congenital defect has been identified...
  
   (or fetal reduction), the practice of reducing the number of fetuses in a multifetal pregnancy
• Reduction (orthopedic surgery)
  Reduction (orthopedic surgery)
  Reduction is a medical procedure to restore a fracture or dislocation to the correct alignment. When a bone fractures, the fragments lose their alignment in the form of displacement or angulation. For the fractured bone to heal without any deformity the bony fragments must be re-aligned to their...
  
  , a medical procedure to restore a fracture or dislocation to the correct alignment
• Ventricular reduction
  Ventricular reduction
  Ventricular reduction is a type of operation in cardiac surgery to reduce enlargement of the heart from cardiomyopathy or ischemic aneurysm formation.-See also:* Batista procedure* Dor procedure...
  
  , a type of operation in cardiac surgery
• Urea reduction ratio (URR), a dimensionless number used to quantify hemodialysis treatment adequacy

Epidemiology

• Relative risk reduction
  Relative risk reduction
  In epidemiology, the relative risk reduction is a measure calculated by dividing the absolute risk reduction by the control event rate.The relative risk reduction can be more useful than the absolute risk reduction in determining an appropriate treatment plan, because it accounts not only for the...
  
  , the absolute risk reduction by the control event rate
• Absolute risk reduction
  Absolute risk reduction
  In epidemiology, the absolute risk reduction or risk difference is the decrease in risk of a given activity or treatment in relation to a control activity or treatment. It is the inverse of the number needed to treat....
  
  , the decrease in risk of a given activity or treatment in relation to a control activity or treatment

Linguistics

• Accent reduction
  Accent reduction
  Accent reduction, also known as elocution or accent modification, is a systematic approach used to learn or adopt a new accent. It is the process of learning the sound system of a language or dialect...
  
  , modifying one's foreign accent towards that of a native speaker
• Vowel reduction
  Vowel reduction
  In phonetics, vowel reduction is any of various changes in the acoustic quality of vowels, which are related to changes in stress, sonority, duration, loudness, articulation, or position in the word , and which are perceived as "weakening"...
  
  , any change in vowel quality perceived as "weakening"
• Relaxed pronunciation
  Relaxed pronunciation
  Relaxed pronunciation is a phenomenon that happens when the syllables of common words are slurred together...
  
  , slurring of syllables of common words
• Definite article reduction
  Definite article reduction
  Definite Article Reduction is the term used in recent linguistic work to refer to the use of vowel-less forms of the definite article the in Northern dialects of English English, for example in the Yorkshire dialect and accent...
  
  , use of vowel-less forms of the English definite article in Northern England

Politics and social policy

• Harm reduction
  Harm reduction
  Harm reduction refers to a range of public health policies designed to reduce the harmful consequences associated with recreational drug use and other high risk activities...
  
  , a philosophy of public health, intended to be a progressive alternative to the prohibition of certain potentially dangerous lifestyle choices
• Immigration reduction
  Immigration reduction
  Immigration reduction refers to a movement in the United States that advocates a reduction in the amount of immigration allowed into the country. Steps advocated for reducing the numbers of immigrants include advocating stronger action to prevent illegal entry and illegal immigration, and...
  
  
• Paperwork reduction, reducing red tape
• Poverty reduction
  Poverty reduction
  Poverty is the state of human beings who are poor. That is, they have little or no material means of surviving—little or no food, shelter, clothes, healthcare, education, and other physical means of living and improving one's life....
  
  
• Risk reduction (disambiguation), risk management by reducing the severity of an eventuated risk
• Reuse
  Reuse
  To reuse is to use an item more than once. This includes conventional reuse where the item is used again for the same function, and new-life reuse where it is used for a different function. In contrast, recycling is the breaking down of the used item into raw materials which are used to make new...
  
  

History

• Lithic reduction
  Lithic reduction
  Lithic reduction involves the use of a hard hammer precursor, such as a hammerstone, a soft hammer fabricator , or a wood or antler punch to detach lithic flakes from a lump of tool stone called a lithic core . As flakes are detached in sequence, the original mass of stone is reduced; hence the...
  
  , in Stone Age toolmaking, to detach lithic flakes from a lump of tool stone
• Reduction (Sweden)
  Reduction (Sweden)
  In the reductions in Sweden, fiefs that had been granted to the Swedish nobility were returned to the Crown.The first reduction under Charles X Gustav of Sweden in 1655 restored a quarter of "donations" made after 1632. In the Great Reduction of 1680 under Charles XI of Sweden the Crown...
  
  , return to the Crown of fiefs that had been granted to the Swedish nobility
• Indian Reductions
  Indian Reductions
  Reductions were settlements founded by the Spanish colonizers of the New World with the purpose of assimilating indigenous populations into European culture and religion.Already since the beginning of the Spanish presence in the Americas, the Crown had been concerned...
  
  , settlements in Spanish America intended to assimilate Indians

Other

• Reduction (cooking)
  Reduction (cooking)
  In cooking, reduction is the process of thickening and intensifying the flavor of a liquid mixture such as a soup, sauce, wine, or juice by boiling....
  
  , the process of thickening or intensifying the flavor of a liquid mixture such as a soup, sauce, wine, or juice by evaporation
• Reduction to practice
  Reduction to practice
  In United States patent law, the reduction to practice is a concept meaning the embodiment of the concept of an invention. The date of this embodiment is critical to the determination of priority between inventors in an interference proceeding....
  
  , in United States patent law, the embodiment of the concept of an invention
• Reduction in rank
  Reduction in rank
  Reduction in rank may refer to two separate concepts:*In military law, a reduction in rank is a demotion in military rank as punishment for a crime or wrongdoing, imposed by a court-martial or other authority...
  
  , military law
• Piano reduction
  Piano reduction
  A piano reduction is sheet music for the piano that was once music for other instruments that was reduced to its most basic components within a two line staff for piano. It is also considered a style of orchestration or music arrangement less well known as contraction scoring, a subset of elastic...
  
  , sheet music for the piano that was once music for other instruments that was reduced to its most basic components within a two line staff for piano
• Ego reduction
  Ego reduction
  The concept of ego reduction occurs in several contexts. The term is predicated on the use of Sigmund Freud's concept of the ego to describe the conscious adult self.Ego reduction has been used* as a goal in Alcoholics Anonymous...
  
  , predicated on the use of Sigmund Freud's concept of the ego