Respuesta :
Answer: This relation is reflexive, antisymmetric and transitive so it is a partial order relation.
Step-by-step explanation: A relation is called a partial order relation if and only if it is reflexive, antisymmetric and transitive. We will check these three characteristics for the given relation.
Reflexive: We need to have that for all [tex]x\in\mathbb{N}[/tex], [tex]xRx[/tex]. This is obviously true since each prime factor of [tex]x[/tex] is certainly a factor of [tex]x[/tex].
Antisymmetric: We need to show that for all [tex]x,y\in\mathbb{N}[/tex] if both [tex]xRy[/tex] and [tex]yRx[/tex] then it must be [tex]x=y[/tex]. To show this suppose that two, otherwise arbitrary, natural numbers [tex]x[/tex] and [tex]y[/tex] are taken such that [tex]xRy[/tex] and [tex]yRx[/tex]. The first of these two says that every prime factor of [tex]x[/tex] is a factor of [tex]y[/tex]. The second one says that every prime factor of [tex]y[/tex] is a factor of [tex]x[/tex]. This means that every prime factor of [tex]x[/tex] is also the prime factor of [tex]y[/tex] and that every prime factor of [tex]y[/tex] is the prime factor of [tex]x[/tex] i.e. that [tex]x[/tex] and [tex]y[/tex] have the same prime factors meaning that they have to be equal.
Transitive: The relation is called transitive if from [tex]xRy[/tex] and [tex]yRz[/tex] then it must also be [tex]xRz[/tex]. To see that this is true of the given relation take some natural numbers [tex]x,y[/tex] and [tex]z[/tex] such that [tex]xRy[/tex] and [tex]yRz[/tex]. The first condition means that each prime factor of [tex]x[/tex] is the factor of [tex]y[/tex] i.e. that all the prime factors of [tex]x[/tex] are contained among the prime factors of [tex]y[/tex]. The second condition means that each prime factor of [tex]y[/tex] is a factor of [tex]z[/tex] i.e. that all the prime factors of [tex]y[/tex] are contained among the prime factors of [tex]z[/tex]. So we have that all of the prime factors of [tex]x[/tex] are contained among the prime factors of [tex]y[/tex] and they themselves are contained among the prime factors of [tex]z[/tex]. This means that certainly all of the prime factors of [tex]x[/tex] are contained among the prime factors of [tex]z[/tex] meaning by the given definition of [tex]R[/tex] that [tex]xRz[/tex] which is what we needed to show.
