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Discrete Mathematical Structures

Exercises 2.2.3 Exercises

2.

State precisely De Morgan’s laws for sets. Be sure to set up any notation that is required.

4.

Let \(A\text{,}\) \(B\text{,}\) \(C\) be sets. Shade the portion of the Venn diagram corresponding to each of these sets.
Inside a box that represents the universal set U there are three ovals that represent sets A, B, and C.  The three sets overlap.  This partitions U into eight regions.
  1. \(\displaystyle A\cup(B\cap C)\)
  2. \(\displaystyle A\cap(B\cap C)\)
  3. \(\displaystyle A\cap(B\cup C)\)
  4. \(\displaystyle (\overline{A} \cap \overline{B}) \cup \overline{C}\)
  5. \(\displaystyle (A - B) - C\)
  6. \(\displaystyle (A - B) \cup (A - C) \cup (B - C)\)

6.

Let \(A\) and \(B\) be sets. Prove that if \(A \subseteq B\text{,}\) then \(A \cup B = B\text{.}\)

11.

Let \(A\) and \(B\) be sets. Prove \(A\lxor B = (A - B) \cup (B - A)\text{.}\)

12.

Let \(A\) and \(B\) be sets.
  1. Prove if \(A \subseteq B\) then \(\overline{B} \subseteq \overline{A}\text{.}\)
  2. Prove if \(\overline{B} \subseteq \overline{A}\) then \(A \subseteq B\text{.}\)