The banana example comes from the MLS-MPM paper[1]. MPM is basically a way of simulating deformable solids using particles. The big thing that the MLS-MPM paper achieved was that the particles wouldn't magically interact with their neighbours on the other side of a thin solid.
The example is kind of ugly, but it's really only trying to illustrate one specific property of their simulation: that the knife can properly separate neighbouring particles from each other without any spooky interactions between the banana on one side of the knife and the banana on the other side.
The example is kind of ugly, but it's really only trying to illustrate one specific property of their simulation: that the knife can properly separate neighbouring particles from each other without any spooky interactions between the banana on one side of the knife and the banana on the other side.
[1]: https://youtu.be/8iyvhGF9f7o | https://dl.acm.org/citation.cfm?id=3201293