Prove that the following languages are not regular. You may use the method developed in class $($pumping lema is not allowed$).$

$?$

$($a$)(10$marks$)$L$=$fw$=$wjw$2$f$0$;$1$g g$.$

$($b$)(10$ marks$)$ The subset of HTML containing only the tags and indicates the begining of a pragraph of text, and tags can be nested, example:

$<\backslash$p$><\backslash$p$>).$ You may asume there is no text content within paragraph tags.