Relational Properties
For each of the following relations on people, decide whether the relation is reflexive, irreflexive, antisymmetric, or transitive:
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"are the same age"
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"is younger than"
This relation is actually asymmetric - different people cannot be younger than each other. -
"have the same parents"
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"is a descendent of"
This relation is irreflexive because a person is not considered to be his/her own descendent. -
"have a parent in common"
This relation is not antisymmetric: different brothers have a parent in common.