In many problems, there can be several different stable matchings. The set of stable matchings has a special structure. David F. Manlove5 proved that both the set of strong stable matchings and the set of super stable matchings form a distributive lattice.
Irving, Robert W. (1994-02-15). "Stable marriage and indifference". Discrete Applied Mathematics. 48 (3): 261–272. doi:10.1016/0166-218X(92)00179-P. https://doi.org/10.1016%2F0166-218X%2892%2900179-P ↩
Manlove, David F. (2002-10-15). "The structure of stable marriage with indifference" (PDF). Discrete Applied Mathematics. 122 (1): 167–181. doi:10.1016/S0166-218X(01)00322-5. ISSN 0166-218X. http://eprints.gla.ac.uk/14/1/ssmi.pdf ↩