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Which of the following is NOT tour of set operations considered as binary operations on the power set of some universe?

a. Symmetric difference has the empty set as its identity.
b. Intersection has the universe as its identity.
c. Union has the empty set as as its identity.
d. Relative complement has the universe as its identity.
e. All statements regarding identities are true.

User Sean L
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1 Answer

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Final answer:

The identity elements for symmetric difference, intersection, and union are correctly identified, but the relative complement does not have the universe as its identity; the empty set is the identity for the relative complement operation.

Step-by-step explanation:

The student is asking about the identity elements for different set operations on the power set of a universe. An identity element is an element in a set that, when used in an operation with any other element of the set, leaves the other element unchanged. For the four set operations mentioned:

  • The symmetric difference has the empty set as its identity because the symmetric difference of any set with the empty set results in the original set.
  • The intersection has the universe as its identity because any set intersected with the universe itself will result in the original set.
  • Union has the empty set as its identity because any set united with the empty set remains unchanged.
  • Relative complement doesn't have the universe as its identity. Instead, the empty set is the identity for the relative complement operation because the relative complement of a set with the universe is the empty set.

Therefore, option d. Relative complement has the universe as its identity, is NOT true when considering binary operations on the power set.

User Thong Yi Xuen
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