Show that the Δ-complex obtained from Δ3 by performing the order-preserving edge identifications [v0,v1]∼[v1,v3] and [v0,v2]∼[v2,v3] deformation retracts onto a Klein bottle. Also, find other pairs of identifications of edges that produce Δ-complexes deformation retracting onto a torus, a 2-sphere, and RP2.