GATE CSE
show that there exists an element $$a \ne e$$,
the identifier $$g$$, such that
$${a^2} = e$$
(b) Consider the set of integers $$\left\{ {1,2,3,4,6,8,12,24} \right\}$$ together with the two binary operations LCM (lowest common multiple) and GCD (greatest common divisor). Which of the following algebraic structures does this represent?
i) Group ii) ring
iii) field iv) lattice
Justify your answer
(1) $$Q\left( x \right) \to P\left( x \right)V \sim R\left( a \right)$$
(2) $$R\left( a \right) \vee \sim Q\left( a \right)$$
(3) $$Q\left( a \right)$$
(4) $$ \sim P\left( y \right)$$
where $$x$$ and $$y$$ are universally quantifies variables, $$a$$ is a constant and $$P, Q, R$$ are monadic predicates.
The language $$\left\{ {{0^n}\,\left| {\,n} \right.} \right.$$ is prime$$\left. \, \right\}$$ is not regular
Regular languages are closed under infinite union.
Union of two recursive languages is recursive
“For every non-deterministic machine $${M_1}$$ there exists an equivalent deterministic machine $${M_2}$$ recognizing the same language“.