Skip to main content
8 events
when toggle format what by license comment
Dec 16, 2021 at 22:16 comment added Pietro Majer Note the correct spelling: Riccati (btw, the word “ricatti” does exist in Italian, and the meaning is: “blackmails”)
Apr 19, 2016 at 6:46 comment added Tom Copeland @L.Spice. tandfonline.com/doi/abs/10.1142/S1402925110000635
Oct 15, 2015 at 16:16 comment added LSpice In my quest for links: Bernoulli numbers and solitons—revisited. It's not on the arXiv, and I can't find a home page for Rzadkowski, so I'm not sure if there's a free version out there.
Oct 10, 2015 at 18:44 comment added Tom Copeland Two others with interesting links: 4) "Bernoulli numbers and solitons - revisited" - Rzadkowski, and 5) "Lie algebras, representations, and analytic semigoups through dual vector fields" - Feinsilver (pp. 44-45), chanoir.math.siu.edu/MATH/Merida/PDF/Merida.pdf.
Oct 10, 2015 at 18:16 comment added Tom Copeland For more on Lie and Ricatti: 1) "An introduction to Lie groups and symplectic geometry" - Bryant, math.duke.edu/~bryant/ParkCityLectures.pdf, 2) "Elie Cartan and geometric duality" - Bryant, math.duke.edu/~bryant/Cartan.pdf, 3) numerous papers by Carinena and associates, e.g., "Integrability of Lie systems through Ricatti equations" arxiv.org/abs/1002.0530.
Dec 9, 2012 at 14:36 comment added Robert Bryant That's true. The point is that the 'evaluation map' from the space of solutions with its natural $\mathbb{RP}^1$-structure to $\mathbb{R}$ given by $u\mapsto u(t_0)$ is an affine chart on the $\mathbb{RP}^1$ for each $t_0$. The constancy of the cross-ratio is then a reflection of the fact that projective transformations of $\mathbb{RP}^1$ preserve the cross-ratio of $4$ points. Of course, this generalizes to all equations of Lie type, replacing $\mathbb{RP}^1$ with the appropriate homogeneous space $M$ and the cross-ratio with appropriate invariant function(s) on products of $M$ with itself.
Dec 9, 2012 at 13:47 comment added Denis Serre The formula given in this answer is related to the fact any four solutions of the Ricatti equation are in constant Cross-ratio.
Dec 8, 2012 at 23:29 history answered Robert Bryant CC BY-SA 3.0