# equivalence relation examples

It is true that if and , then .Thus, is transitive. Problem 2. The relation is symmetric but not transitive. Examples of Equivalence Relations. if there is with . This is true. An example from algebra: modular arithmetic. If we consider the equivalence relation as de ned in Example 5, we have two equiva-lence … Example 6. Example. This is false. Equality modulo is an equivalence relation. Let . Practice: Modular multiplication. If x and y are real numbers and , it is false that .For example, is true, but is false. Show that the less-than relation on the set of real numbers is not an equivalence relation. Then Ris symmetric and transitive. Equivalence relations. Modular addition and subtraction. The last examples above illustrate a very important property of equivalence classes, namely that an equivalence class may have many di erent names. What about the relation ?For no real number x is it true that , so reflexivity never holds.. (For organizational purposes, it may be helpful to write the relations as subsets of A A.) The quotient remainder theorem. But di erent ordered … Theorem. Some more examples… Let Rbe a relation de ned on the set Z by aRbif a6= b. It was a homework problem. Answer: Thinking of an equivalence relation R on A as a subset of A A, the fact that R is re exive means that Proof. Let be an integer. First we'll show that equality modulo is reflexive. Equivalence relations A motivating example for equivalence relations is the problem of con-structing the rational numbers. It provides a formal way for specifying whether or not two quantities are the same with respect to a given setting or an attribute. This is the currently selected item. The following generalizes the previous example : Definition. We say is equal to modulo if is a multiple of , i.e. For example, if [a] = [2] and [b] = [3], then [2] [3] = [2 3] = [6] = [0]: 2.List all the possible equivalence relations on the set A = fa;bg. Solution: Relation $\geq$ is reflexive and transitive, but it is not symmetric. A rational number is the same thing as a fraction a=b, a;b2Z and b6= 0, and hence speci ed by the pair ( a;b) 2 Z (Zf 0g). Example 5: Is the relation $\geq$ on $\mathbf{R}$ an equivalence relation? The set [x] ˘as de ned in the proof of Theorem 1 is called the equivalence class, or simply class of x under ˘. De nition 4. Problem 3. The intersection of two equivalence relations on a nonempty set A is an equivalence relation. We have already seen that $$=$$ and $$\equiv(\text{mod }k)$$ are equivalence relations. Examples of Reflexive, Symmetric, and Transitive Equivalence Properties An Equivalence Relationship always satisfies three conditions: The equivalence relation is a key mathematical concept that generalizes the notion of equality. An equivalence relation is a relation that is reflexive, symmetric, and transitive. If two elements are related by some equivalence relation, we will say that they are equivalent (under that relation). Proof. In the above example, for instance, the class of … Let ˘be an equivalence relation on X. Then is an equivalence relation. Proof. Modulo Challenge (Addition and Subtraction) Modular multiplication. Equality Relation We write X= ˘= f[x] ˘jx 2Xg. For example, take a look at numbers $4$ and $1$; $4 \geq 1$ does not imply that $1 \geq 4$. Modular exponentiation. Conversely, any partition induces an equivalence relation.Equivalence relations are important, because often the set S can be ’transformed’ into another set (quotient space) by considering each equivalence class as a single unit. An equivalence relation on a set induces a partition on it. Practice: Modular addition. Provides a formal way For specifying whether or not two quantities are the same with respect to a given or. 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