Figure 4: Apparent intersection (due to avoided crossing) of the axisymmetric first quasi-radial overtone () and the first overtone of the p-mode (in the Cowling approximation). Frequencies are normalized by , where is the central energy density of the star. The rotational frequency at the mass-shedding limit is 0.597 (in the above units). Along continuous sequences of computed frequencies, mode eigenfunctions are exchanged at the avoided crossing. Defining quasi-normal mode sequences by the shape of their eigenfunction, the sequence (filled boxes) appears to intersect with the sequence (triangle), but each sequence shows a discontinuity, when the region of apparent intersection is well resolved. (Figure 3 of Yoshida and Eriguchi [330]; used with permission.)