Find the least upper bound and greatest lower bound of \( S = \{X, Y, Z\} \) if they exist, of the poset whose Hasse diagram is shown below:
Step 1: Understanding the Hasse diagram.
In a Hasse diagram, the least upper bound (LUB) is the smallest element that is greater than or equal to all elements in the set, and the greatest lower bound (GLB) is the largest element that is less than or equal to all elements in the set.
Step 2: Identify the least upper bound.
The least upper bound of the set \( \{X, Y, Z\} \) is the smallest element that is greater than or equal to both \( X \), \( Y \), and \( Z \). Based on the diagram, the least upper bound is \( T \).
Step 3: Identify the greatest lower bound.
The greatest lower bound of the set \( \{X, Y, Z\} \) is the largest element that is less than or equal to both \( X \), \( Y \), and \( Z \). From the diagram, the greatest lower bound is \( Y \).
Step 4: Conclusion.
Thus, the correct answer is (4) The least upper bound is \( T \) and the greatest lower bound is \( Y \).
Suppose \( D_1 = (S_1, \Sigma, q_1, F_1, \delta_1) \) and \( D_2 = (S_2, \Sigma, q_2, F_2, \delta_2) \) are finite automata accepting languages \( L_1 \) and \( L_2 \), respectively. Then, which of the following languages will also be accepted by the finite automata:
(A) \( L_1 \cup L_2 \)
(B) \( L_1 \cap L_2 \)
(C) \( L_1 - L_2 \)
(D) \( L_2 - L_1 \)
Choose the correct answer from the options given below:
Match LIST-I with LIST-II \[\begin{array}{|c|c|c|}\hline \text{ } & \text{LIST-I} & \text{LIST-II} \\ \hline \text{A.} & \text{A Language L can be accepted by a Finite Automata, if and only if, the set of equivalence classes of $L$ is finite.} & \text{III. Myhill-Nerode Theorem} \\ \hline \text{B.} & \text{For every finite automaton M = $(Q, \Sigma, q_0, A, \delta)$, the language L(M) is regular.} & \text{II. Regular Expression Equivalence} \\ \hline \text{C.} & \text{Let, X and Y be two regular expressions over $\Sigma$. If X does not contain null, then the equation $R = Y + RX$ in R, has a unique solution (i.e. one and only one solution) given by $R = YX^*$.} & \text{I. Arden's Theorem} \\ \hline \text{D.} & \text{The regular expressions X and Y are equivalent if the corresponding finite automata are equivalent.} & \text{IV. Kleen's Theorem} \\ \hline \end{array}\]
\[\text{Matching List-I with List-II}\]
Choose the correct answer from the options given below: