Here are some examples of the post that are currently tagged [tag:graph] and this tag is used in the "broader sense". (So they might need retagging, if the consensus is that this tag is for questions about plotting graphs of functions.)

* https://math.stackexchange.com/questions/268206/lower-semicontinuity-and-closed-graph
* https://math.stackexchange.com/questions/304601/fm-1-to-m-2-is-continuous-iff-its-graph-is-compact
* https://math.stackexchange.com/questions/326902/does-closed-graph-imply-closed-range
* https://math.stackexchange.com/questions/342007/operator-graph-question