This is a follow up to Harrison's question: why planar graphs are so exceptional. I would like to ask about (and collect answers to) various notions, in graph theory and beyond graph theory (topology; algebra) that generalize the notion of planar graphs. And , and how properties of planar graphs extend in these wider contexts.

This is a follow up to Harrison's question: why planar graphs are so exceptional. I would like to ask about (and collect answers ) to) various notions, in graph theory and beyond graph theory (topology; algebra) that generalize the notion of planar graphs. And how properties of planar graphs extend in these wider contexts.

This is a follow up to Harrison's question: "why planar graphs are so exceptional". I would like to ask (and collect answers) to various notions, in graph theory and beyond graph theory (topology; algebra) that generalize the notion of planar graphs. And how properties of planar graphs extend in these wider contexts.

This is a follow up to Harrison's question: "why planar graphs are so exceptional". I would like to ask (and collect answers) to various notions, in graph theory and beyond graph theory (topology; algebra) that generalize the notion of planar graphs. And how properties of planar graphs extend in these wider contexts.