Build PDA that recognizes the language:
$L=\{x\in\{a,b\}^* \text{and } x\neq ww \text{ for any } w \in\{a,b\}^* \}$
How would you approach this? I was thinking I could do something with $ww^R$, but the problem is that I don't know if I am allowed to read the reversal of the remaining string at any point