If a language L1 is given as anbn and L2 is given as {a,b}* , then the language L1 - L2 will be : regular or CFL and why ?
My doubt is that since L2 is a regular language and L1 is CFL and L2 will contain all strings in L1, so L1 - L2 will give {} which is regular.
But I found in some book the since L1 is CFL and L2 is regular L1 - L2 can be written as $L1\cap L2¯$ ( CFL intersection regular complement ). Complement of regular is regular and intersection of CFL with regular is closed and the language will be CFL.
Which one is right and why ?