Non-orientable Lagrangian surfaces in rational 4-manifolds

Bo Dai, Chung-I Ho, Tian-Jun Li

We show that for any nonzero class $A$ in $H_2(X;{\mathbb{Z}}_2)$ in a rational 4-manifold $X$, $A$ is represented by a nonorientable embedded Lagrangian surface L (for some symplec…