Theese are also known as "Topology-disturbing objects". This article (also by Sugihara Kokichi) goes into a lot more details: https://www.tandfonline.com/doi/fu

Theese are also known as "Topology-disturbing objects". This article (also by Sugihara Kokichi) goes into a lot more details: https://www.tandfonline.com/doi/full/10.1080/17513472.2017.1368133 https://www.tandfonline.com/doi/full/10.1080/17513472.2017.1... See also the discussion here: https://news.ycombinator.com/item?id=21602121 https://news.ycombinator.com/item?id=21602121