Dissociation of disclinations are used to model these phenomena in KTHNY theory. Above the upper critical dimension, these phenomena belong to the same universality (10[1])class (10[1])predicted by mean-field (10[1])theory. (10[1])An argument (10[1])using the favorability of spontaneously forming domain walls was used by Rudolph Peierls (“PIE-erls”) to prove one of these (-5[1])phenomena (10[1])exists in two (10[1])dimensions (10[1]-5[1])or higher (10[2])for a certain (10[1])lattice model. (10[2])Landau (10[1]-5[1])theory (10[2])classifies (10[1])these phenomena (10[3])into (10[1])first- (10[2]-5[1])or second-order (10[4])based (10[4])on whether (10[2])the (10[1])change (10[2])in their order parameter is discontinuous. (10[2]-5[1])These phenomena include the shift (10[3])between (10[1])paramagnetic (10[4])and ferromagnetic (10[1])ordering (10[4])at the (10[1])Curie (10[1])point. (10[1])On pressure–temperature diagrams, (10[2])these (10[1])events (10[1])are represented (10[5])by (10[3])crossing (10[4]-5[1])a (10[1])coexistence (10[2])curve. (10[6]-5[1])For (10[1])10 points, (10[1])name these (10[1])phenomena (10[3])in which a (-5[1])material changes (10[2]-5[1])between (10[2]-5[1])different (10[2])states (10[2]-5[1])of matter. (10[8])■END■ (10[14]0[3])