Think [math]\le[/math]. Also, i'm curious to know since relations can both be neither symmetric and anti-symmetric, would R = {(1,2),(2,1),(2,3)} be an example of such a relation? Symmetric or antisymmetric are special cases, most relations are neither (although a lot of useful/interesting relations are one or the other). Apply it to Example 7.2.2 to see how it works. For example: If R is a relation on set A = {12,6} then {12,6}∈R implies 12>6, but {6,12}∉R, since 6 is not greater than 12. ? Yes. Or we can say, the relation R on a set A is asymmetric if and only if, (x,y)∈R (y,x)∉R. Note: Asymmetric is the opposite of symmetric but not equal to antisymmetric. How can a relation be symmetric an anti symmetric? How can a relation be symmetric and anti-symmetric? the truth holds vacuously. Question: How Can A Matrix Representation Of A Relation Be Used To Tell If The Relation Is: Reflexive, Irreflexive, Symmetric, Antisymmetric, Transitive? Thus, it will be never the case that the other pair you're looking for is in $\sim$, and the relation will be antisymmetric because it can't not be antisymmetric, i.e. (2,1) is not in B, so B is not symmetric. Antisymmetric means that the only way for both [math]aRb[/math] and [math]bRa[/math] to hold is if [math]a = b[/math]. A relation can be both symmetric and antisymmetric. Given that P ij 2 = 1, note that if a wave function is an eigenfunction of P ij , then the possible eigenvalues are 1 and –1. A relation R on a set A is symmetric iff aRb implies that bRa, for every a,b ε A. A relation R on a set A is antisymmetric iff aRb and bRa imply that a = b. Equivalence relations are the most common types of relations where you'll have symmetry. This question hasn't been answered yet Ask an expert. A relation can be neither symmetric nor antisymmetric. It can be reflexive, but it can't be symmetric for two distinct elements. Since (1,2) is in B, then for it to be symmetric we also need element (2,1). If a relation \(R\) on \(A\) is both symmetric and antisymmetric, its off-diagonal entries are all zeros, so it is a subset of the identity relation. – antisymmetric states 㱺 fermions half-integer spin • Pauli from properties of electrons in atoms – symmetric states 㱺 bosons integer spin • Considerations related to electromagnetic radiation (photons) • Can also consider quantization of “field” equations – … Antisymmetric relation is a concept of set theory that builds upon both symmetric and asymmetric relation in discrete math. It is an interesting exercise to prove the test for transitivity. Symmetry Properties of Relations: A relation {eq}\sim {/eq} on the set {eq}A {/eq} is a subset of the Cartesian product {eq}A \times A {/eq}. Whether the wave function is symmetric or antisymmetric under such operations gives you insight into whether two particles can occupy the same quantum state. At its simplest level (a way to get your feet wet), you can think of an antisymmetric relation of a set as one with no ordered pair and its reverse in the relation.