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Exercises 11.3 Exercises

Given these matrices, answer the following questions or compute the following matrices (if they exist).

\begin{equation*} A = \left( \begin{array}{cc} 0 \amp 1 \\ 1 \amp 0 \end{array} \right) \qquad B = \left( \begin{array}{cc} 1 \amp 1 \\ 0 \amp 0 \\ 1 \amp 0 \end{array} \right) \end{equation*}
\begin{equation*} C = \left( \begin{array}{cc} 1 \amp 0 \\ 1 \amp 1 \end{array} \right) \qquad D = \left( \begin{array}{ccc} 1 \amp 1 \amp 0 \\ 0 \amp 1 \amp 0 \\ 1 \amp 0 \amp 1 \end{array} \right) \end{equation*}
1.

Calculate \(A \vee C\text{.}\)

2.

Calculate \(C \wedge A\text{.}\)

3.

Calculate \(A \wedge B\text{.}\)

4.

Calculate \(A \odot B\text{.}\)

5.

Calculate \(B \odot A\text{.}\)

6.

Calculate \(D \odot B\text{.}\)

7.

Calculate \(D^{[2]}\) (which is the same as \(D \odot D\)).

8.

Calculate

\begin{equation*} \left( \begin{array}{rrr} 1 \amp 0 \amp 1 \\ 0 \amp 1 \amp 1 \end{array} \right) \vee \left( \begin{array}{rrr} 0 \amp 0 \amp 1 \\ 1 \amp 0 \amp 1 \end{array} \right) \end{equation*}

or say the matrix doesn't exist.

9.

Calculate

\begin{equation*} \left( \begin{array}{cc} 1 \amp 0 \\ 0 \amp 1 \\ 1 \amp 1 \\ 0 \amp 0 \end{array} \right) \wedge \left( \begin{array}{cc} 0 \amp 0 \\ 1 \amp 1 \\ 0 \amp 1 \\ 1 \amp 0 \end{array} \right) \end{equation*}

or say the matrix doesn't exist.

10.

Calculate

\begin{equation*} \left( \begin{array}{ccc} 0 \amp 1 \amp 1 \\ 1 \amp 0 \amp 1 \end{array} \right) \odot \left( \begin{array}{cccc} 1 \amp 0 \amp 0 \amp 1 \\ 0 \amp 0 \amp 1 \amp 1 \\ 1 \amp 0 \amp 0 \amp 0 \end{array} \right) \end{equation*}

or say the matrix doesn't exist.

11.

Calculate

\begin{equation*} \left( \begin{array}{rrrr} 0 \amp 1 \amp 1 \amp 1 \\ 1 \amp 0 \amp 1 \amp 0 \\ 0 \amp 0 \amp 1 \amp 1 \end{array} \right)^T \end{equation*}
12.

Let \(\Sigma = \{0,1\}\text{,}\) \(n\) be a positive integer, and let \(\Sigma^n\) be the set of all bit strings of length \(n\text{.}\) Describe a Boolean algebra structure on \(\Sigma^n\text{.}\) In other words, define the meet, join, and complement operations and give examples, and tell what the bottom and top objects are.

Solution.

The complement of a string is the string with each \(1\) replaced by a \(0\) and vice-versa, e.g. \(\neg 0101 = 1010\text{.}\)

The meet of two strings has a \(1\) only in the digits where both strings had a \(1\) and \(0\)s elsewhere, e.g. \(1101 \wedge 0110 = 0100\text{.}\)

The join of two strings has a \(1\) anywhere at least one of the two strings has a \(1\text{,}\) e.g. \(10110 \vee 00101 = 10111\text{.}\)

The top element is the string of all ones and the bottom element is the string of all zeros.