The definition presented here is due essentially to Charles Ehresmann. However, it is different from, though related to, what is commonly called an Ehresmann connection. It is also different from, though related to, what is commonly called a Cartan connection. See Kobayashi (1957) and Sharpe (1997) for a survey of some of the various types of connections and the relations between them. Kobayashi, Shochichi (1957), "Theory of connections", Annali di Matematica Pura ed Applicata, Series 4, 43 (1): 119–194, doi:10.1007/BF02411907, S2CID120972987, Sharpe, Richard W. (1997), Differential Geometry: Cartan's Generalization of Klein's Erlangen Program, Springer-Verlag, ISBN0387947329
A similar argument applies to the transitive action by conjugation of SU(2) on matrices F = 2Q − I with Q a rank one projection in M2(C). This action is trivial on ± I, so passes to a transitive action of SO(3) with stabilizer subgroup SO(2), showing that these matrices provide another model for S2. This is standard material in gauge theory on SU(2); see for example Narasimhan & Ramadas (1979). Narasimhan, M.S.; Ramadas, T. R. (1979), "Geometry of SU(2) gauge fields", Comm. Math. Phys., 67 (2): 121–136, Bibcode:1979CMaPh..67..121N, doi:10.1007/BF01221361, S2CID118840198
A similar argument applies to the transitive action by conjugation of SU(2) on matrices F = 2Q − I with Q a rank one projection in M2(C). This action is trivial on ± I, so passes to a transitive action of SO(3) with stabilizer subgroup SO(2), showing that these matrices provide another model for S2. This is standard material in gauge theory on SU(2); see for example Narasimhan & Ramadas (1979). Narasimhan, M.S.; Ramadas, T. R. (1979), "Geometry of SU(2) gauge fields", Comm. Math. Phys., 67 (2): 121–136, Bibcode:1979CMaPh..67..121N, doi:10.1007/BF01221361, S2CID118840198
The definition presented here is due essentially to Charles Ehresmann. However, it is different from, though related to, what is commonly called an Ehresmann connection. It is also different from, though related to, what is commonly called a Cartan connection. See Kobayashi (1957) and Sharpe (1997) for a survey of some of the various types of connections and the relations between them. Kobayashi, Shochichi (1957), "Theory of connections", Annali di Matematica Pura ed Applicata, Series 4, 43 (1): 119–194, doi:10.1007/BF02411907, S2CID120972987, Sharpe, Richard W. (1997), Differential Geometry: Cartan's Generalization of Klein's Erlangen Program, Springer-Verlag, ISBN0387947329
A similar argument applies to the transitive action by conjugation of SU(2) on matrices F = 2Q − I with Q a rank one projection in M2(C). This action is trivial on ± I, so passes to a transitive action of SO(3) with stabilizer subgroup SO(2), showing that these matrices provide another model for S2. This is standard material in gauge theory on SU(2); see for example Narasimhan & Ramadas (1979). Narasimhan, M.S.; Ramadas, T. R. (1979), "Geometry of SU(2) gauge fields", Comm. Math. Phys., 67 (2): 121–136, Bibcode:1979CMaPh..67..121N, doi:10.1007/BF01221361, S2CID118840198