Centrality

Not all notes pull equal weight. Centrality is the network-research term for how important a note is to the structure around it: how much of the network leans on it. Two kinds are worth knowing for notes; the rest are academic.

Hubs: degree centrality

The simplest centrality is just degree: how many Links a note has (see Network Measures). Your most-connected notes are your hubs: anchor ideas that many others connect to or through, the de-facto tables of contents that emerge on their own. They’re where reviewing pays off, because touching a hub touches everything around it.

The opposite end is the orphan: a note with zero links, and so zero centrality. The NetworkMap sizes every dot by its degree, so your hubs are the big dots and your orphans are the small ones sitting off on their own.

Bridges: betweenness centrality

A note can be important without being a hub. Betweenness measures how often a note sits on the path between other notes, and the ones that score high are bridges: they connect otherwise-separate communities of your network.

Bridges are worth prizing. A bridge is where an idea from one domain reaches another, and that is where most original thinking happens.

You don’t need to compute betweenness; it’s fussy and unreliable at small scale. Just notice, when two clusters on your map are joined by a single note, that you’ve found a bridge worth keeping.

What about PageRank, closeness, eigenvector?

Network science has many more centralities, and they’re genuinely interesting. For a personal notebook they’re overkill: they need real scale to mean anything, and chasing a centrality score is exactly the system-perfecting trap the method warns against. Degree tells you your hubs; a glance at the map tells you your bridges. That is enough.

The point

Centrality answers one practical question: which notes matter most? Find your hubs and review them, spot your bridges and protect them, give your orphans a link. Then close the map and write the next note.