Question

Boolean algebra. I'll write problem in comment.

Answer 1

a or not a = 1

Answer 2

not a or not b or not (a and b)

Answer 3

a implies not a.

Answer 4

Let L={a,b,c,d,e,f}, P(L) is power set of L and \[\le\] is order relation on P(L) defined as:

if r and t are relations, then \[r \le t\] iff every block in r is subset of some block in t. Show that lattice \[(P(L), \le )\] is not modular.