Reduction (complexity)

Many-one reduction

In computability theory and computational complexity theory, a many-one reduction (also called mapping reduction) is a reduction which converts instances of one decision problem into instances of a second decision problem where the instance reduced to is in the language if the initial instance was in its language and is not in the language if the initial instance was not in its language . Thus if we can decide whether instances are in the language , we can decide whether instances are in its language by applying the reduction and solving . Thus, reductions can be used to measure the relative computational difficulty of two problems. It is said that reduces to if, in layman's terms is harder to solve than . That is to say, any algorithm that solves can also be used as part of a (otherwise relatively simple) program that solves . Many-one reductions are a special case and stronger form of Turing reductions. With many-one reductions, the oracle (that is, our solution for B) can be invoked only once at the end, and the answer cannot be modified. This means that if we want to show that problem A can be reduced to problem B, we can use our solution for B only once in our solution for A, unlike in Turing reduction, where we can use our solution for B as many times as needed while solving A. This means that many-one reductions map instances of one problem to instances of another, while Turing reductions compute the solution to one problem, assuming the other problem is easy to solve. The many-one reduction is more effective at separating problems into distinct complexity classes. However, the increased restrictions on many-one reductions make them more difficult to find. Many-one reductions were first used by Emil Post in a paper published in 1944. Later Norman Shapiro used the same concept in 1956 under the name strong reducibility. (Wikipedia).

Video thumbnail

Multiplying and Dividing Negative Numbers

"Multiply or divide a mixture of positive and negative numbers."

From playlist Number: Negative Numbers

Video thumbnail

How to Compute a One Sided limit as x approaches from the right

In this video I will show you How to Compute a One Sided limit as x approaches from the right.

From playlist One-sided Limits

Video thumbnail

Ex: Linear Equation Application with One Variable - Number Problem

This video provides and example of how to solve a number problem using a linear equation with one variable. One number is a multiple of the other. The difference is a constant. Find the two numbers. Library: http://mathispower4u.com Search: http://mathispower4u.wordpress.com

From playlist Whole Number Applications

Video thumbnail

Dividing by Powers of Ten

This video explains how to divide whole numbers and decimals by powers of ten. Search Video Library at http://www.mathispower4u.wordpress.com

From playlist Number Sense - Decimals, Percents, and Ratios

Video thumbnail

Zero Factorial: Why is 0! = 1?

This video provides justification as to why 0!=1 using patterns and the meaning of a permutation. http://mathispower4u.com

From playlist Using the Binomial Theorem / Combinations

Video thumbnail

Computing a One Sided Limit with an Absolute Value Function

In this video I do an example of Computing a One Sided Limit with an Absolute Value Function.

From playlist One-sided Limits

Video thumbnail

Multiplying Whole Numbers

This video explains how to multiply using whole numbers. http://mathispower4u.yolasite.com/

From playlist Multiplying and Dividing Whole Numbers

Video thumbnail

Limits Involving a Fraction

Thanks to all of you who support me on Patreon. You da real mvps! $1 per month helps!! :) https://www.patreon.com/patrickjmt !! Limits Involving Fractions. Here we have a 0/0 type of limit which we can evaluate by simplifying the fraction.

From playlist All Videos - Part 3

Video thumbnail

26. Chemical and biological oxidation/reduction reactions

MIT 5.111 Principles of Chemical Science, Fall 2008 View the complete course: http://ocw.mit.edu/5-111F08 Instructor: Catherine Drennan, Elizabeth Vogel Taylor License: Creative Commons BY-NC-SA More information at http://ocw.mit.edu/terms More courses at http://ocw.mit.edu

From playlist MIT 5.111 Principles of Chemical Science, Fall 2008

Video thumbnail

On some fine-grained questions in algorithms and complexity – V. Vassilevska Williams – ICM2018

Mathematical Aspects of Computer Science Invited Lecture 14.8 On some fine-grained questions in algorithms and complexity Virginia Vassilevska Williams Abstract: In recent years, a new “fine-grained” theory of computational hardness has been developed, based on “fine-grained reductions”

From playlist Mathematical Aspects of Computer Science

Video thumbnail

Bala Krishnamoorthy (10/20/20): Dimension reduction: An overview

Bala Krishnamoorthy (10/20/20): Dimension reduction: An overview Title: Dimension reduction: An overview Abstract: We present a broad overview of various dimension reduction techniques. Referred to also as manifold learning, we review linear dimension reduction techniques, e.g., principa

From playlist Tutorials

Video thumbnail

NP Completeness III - More Reductions - Lecutre 17

All rights reserved for http://www.aduni.org/ Published under the Creative Commons Attribution-ShareAlike license http://creativecommons.org/licenses/by-sa/2.0/ Tutorials by Instructor: Shai Simonson. http://www.stonehill.edu/compsci/shai.htm Visit the forum at: http://www.coderisland.c

From playlist ArsDigita Algorithms by Shai Simonson

Video thumbnail

Lec 25 | MIT 5.111 Principles of Chemical Science, Fall 2005

Oxidation/Reduction (Prof. Catherine Drennan) View the complete course: http://ocw.mit.edu/5-111F05 License: Creative Commons BY-NC-SA More information at http://ocw.mit.edu/terms More courses at http://ocw.mit.edu

From playlist MIT 5.111 Principles of Chemical Science, Fall 2005

Video thumbnail

General Chemistry 1C. Lecture 16. Electrochemistry Pt. 1.

UCI Chem 1C General Chemistry (Spring 2013) Lec 16. General Chemistry -- Electrochemistry -- Part 1 View the complete course: http://ocw.uci.edu/courses/chem_1c_general_chemistry.html Instructor: Ramesh D. Arasasingham, Ph.D. License: Creative Commons BY-NC-SA Terms of Use: http://ocw.uci

From playlist Chemistry 1C: General Chemistry

Video thumbnail

Kęstutis Česnavičius - Grothendieck–Serre in the quasi-split unramified case

Correction: The affiliation of Lei Fu is Tsinghua University. The Grothendieck–Serre conjecture predicts that every generically trivial torsor under a reductive group scheme G over a regular local ring R is trivial. We settle it in the case when G is quasi-split and R is unramified. To ov

From playlist Conférence « Géométrie arithmétique en l’honneur de Luc Illusie » - 5 mai 2021

Video thumbnail

NP Completeness II & Reductions - Lecture 16

All rights reserved for http://www.aduni.org/ Published under the Creative Commons Attribution-ShareAlike license http://creativecommons.org/licenses/by-sa/2.0/ Tutorials by Instructor: Shai Simonson. http://www.stonehill.edu/compsci/shai.htm Visit the forum at: http://www.coderisland.c

From playlist ArsDigita Algorithms by Shai Simonson

Video thumbnail

Introduction to Elliptic Curves 3 by Anupam Saikia

PROGRAM : ELLIPTIC CURVES AND THE SPECIAL VALUES OF L-FUNCTIONS (ONLINE) ORGANIZERS : Ashay Burungale (California Institute of Technology, USA), Haruzo Hida (University of California, Los Angeles, USA), Somnath Jha (IIT - Kanpur, India) and Ye Tian (Chinese Academy of Sciences, China) DA

From playlist Elliptic Curves and the Special Values of L-functions (ONLINE)

Video thumbnail

Convert Percentages to Fractions

This video explains how to convert percentages to fractions. http://mathispower4u.com

From playlist Introduction to Percentages

Video thumbnail

Minicourse: Deformations of path algebras of quivers with relations. Lecture III

The minicourse consists of 4 lectures. Lecturers: Severin Barmeier and Zhengfang Wang Path algebras of quivers with relations naturally occur throughout representation theory and algebraic geometry — for example in the representation theory of finite-dimensional algebras, as the coordin

From playlist Minicourse: Deformations of path algebras of quivers with relations, JTP New Trends in Representation Theory

Related pages

If and only if | NL (complexity) | Decision problem | Universal Turing machine | Polynomial-time reduction | Formal language | Turing reduction | Co-NP | Relation (mathematics) | Decidability (logic) | Transitive relation | Preorder | Reflexive relation | L (complexity) | Computability theory | NP (complexity) | Halting problem | Log-space reduction | Computational complexity theory | P (complexity) | Reduction (complexity) | Algorithm | Power set | PSPACE