Just saying, conical cuts are not invented by V-Cubes. They have no right to claim the design as their own, yet they shamelessly included it in their patent.
Plus, DaYan was the first to actually use conical cuts in the 3x3x3, V-Cube's original idea of a 3x3 (according to the patent drawing) was the incredibly ineffective "winged" design. Their freedom to use a different design for the final product is completely irrelavent here.
It cannot be determined whether either of the two independently came up with the idea of using conical cuts in the 3x3x3 cube.
Maybe it's like Newton and Leibniz, they both came up with the idea of modern calculus on their own, just the matter of who revealed it first.
In my opinion, even if DaYan did "copy" V-cube's design, they at least put a lot of effort into perfecting the design as well as adding lots of innovative ideas in the final product. The Dayan Guhong is more than just conical cuts, you know; the usage of interior curvature is what accounts for the crazy foward and reverse corner-cutting.
V-cubes, on the other hand, are lazier than Porsche designers.
PS:
An interesting thing to note -- DaYan, too, used the winged design in the ZhanChi. Though much more subtle, it is definitely the same idea as the original V-Cubes 3x3
PS2: V-Cubes DEFINITELY ripped the torpedos design off DaYan. Case closed for this one.