The AlgebraicKernelForCircles concept is meant to provide the curved kernel with all the algebraic functionalities required for the manipulation of circular arcs.
Algebraic_kernel_for_circles_2_2
A model of AlgebraicKernelForCircles is supposed to provide
CircularKernel
CGAL::Circular_kernel_2<LinearKernel,AlgebraicKernelForCircles>