Complex sentence: Projective geometry, like affine and Euclidean geometry, can also be developed from the Erlangen program of Felix Klein; projective geometry is characterized by invariants under transformations of the projective group.
Split into simpler sentences: Projective geometry, like affine and Euclidean geometry, can also be developed from the Erlangen program of Felix Klein. In Klein's Erlangen program, projective geometry is characterized by invariants under transformations of the projective group.