In intuitionistic Kripke semantics, a frame is a poset of worlds $(W, \le)$ and a forcing relation $\Vdash$ that is monotone (i.e., if $w \Vdash P$ and $w \le u$, then $u \Vdash P$). Let $W = \{w_1, w_2, w_3\}$ with $w_1 \le w_2$ and $w_1 \le w_3$ (where $w_2, w_3$ are incomparable). Let the valuation of a proposition $P$ be $V(P) = \{w_2\}$. Which of the following formulas is NOT forced at the root world $w_1$?