As a user of Maple 13, namely in computations on General Relativity & Tensor Calculus, I would like to let you know I just got, using Maple 13, the WRONG SIGN (positive Riemann scalar curvature in stead of correct NEGATIVE Riemann scalar curvature) in studying a threefold used as a 'Public Space' by Milne many years ago.

The square of the distance on the said threefold is dE^2=dR^2+(c*t0)^2*sinh(R/(c*t0))^2*(dtheta^2+sin(theta)^2*dphi^2) and you might be interested to learn that all components of the RIEMANN tensor returned by Maple have the WRONG SIGN, with the consequence that all components of the RICCI tensor & the scalar Riemann curvature are all of WRONG SIGN, as you might see yourself using the appropriate tensor Package built in the aforementioned software.

Best regards,


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