i need examplees where the ricci scalar is constant but nonzero . Particulary i search examples of line element. Pd: this is not a homework,
I'm not sure if you are referring to spaces or spacetimes. If spaces, then maximally symmetric spaces have the property that the Ricci scalar is constant everywhere. In 3 dimensions these are the 3-sphere and the 3-hyperboloid (and Euclidean space, but there R=0). If you are referring to spacetimes, then the Ricci scalar is proportional to the trace of the stress tensor (T), so you need to find some spacetime with constant T everywhere. I can't think of any examples of the top of my head.