Question: how do you set up the Arnold ambient_occlusion shader so that it ignores self-occlusion?

Let’s start with the default ambient occlusion. here’s a sphere and a plane. Each has it’s own Ambient Occlusion shader. For the sphere, Ambient Occlusion.Black is Red.

Now, let’s disable Receives Shadows on the sphere.
That means no occlusion based on the plane (shadow rays from the sphere ignore the plane); but there’s still self-occlusion.

Next, Cast Shadows disabled. No self-occlusion, but no ambient occlusion on the plane either

And finally, Self Shadows disabled. Now, there’s no self-occlusion. The ambient occlusion on the sphere is coming solely from the plane