1. y R x means y is related to x through a relation R.
2.x R y means x is related to y through a relation R.
1. Upper Bound:
An elements x such that all the elements of set or poset 'A'are related. ie.
y R x : ∀ y ∈ A and x ∈ A
x is called uppar bound.
2. Lower bound :
An element y is called lower bound if y R x : ∀ x ∈ A and y ∈ A.
3. Minimal Elements:
Informally, x is called a minimal element if no element is related to x.
It is present at a lower level.
4. Maximal Elements:
- Informally, x is called maximal elements if x is not related to any other elements.
- It is not compulsory that we always get unique maximal and minimal elements. We can have more than one maximal and minimal elements.