If it feels difficult to construct a spaced repetition card, it’s probably because that section of one’s knowledge graph is not yet broken down into atomic nodes with clear and simple connections to each other.
Any well-understood (i.e.
chunked) node is defined by its relationship to other well-understood nodes, and one marker of a well-understood node is if it has a term or phrase it can be identified by. Using good
Concept Handles might help when trying to flesh out an idea area.
A set equipped with an operation that combines any two elements to form a third element while being associative as well as having an identity elements and inverse elements.
Each concept (represented by the bold) could be a connected node, and in a sense, one must first fully understand each of those connected nodes to then understand what a group is.
How each concept should be broken down may be subjective to some degree: one has to decide how to make a concept atomic (for this example, if it has a wikipedia page I considered it a concept of its own).
Similarly, concepts are related to each other in many ways, but not necessarily all those relations are relevant for “knowing” the concept (i.e. putting it on a spaced repetition card).
Group theory is a lot more complicated than simply knowing what a group is, so the node group will be connected to a lot of other concepts. But its definition should be well-scoped in order to be atomic and made into a spaced repetition card.