On the sagenb github site (https://github.com/sagemath/sagenb/issues/402):
Hi there, I tried to verify with Sage that P^2 is projective. Unfortunately, Sage replied with 'false'. Here is what I tried: P2=toric_varieties.P2(); P2.is_projective() The last line returned 'false'. The same happens for e.g. P1xP1. [I am running SageMath version 7.2, Release Date: 2016-05-15] Is this a bug? Thank you! -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at https://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
