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Core point

A core point is a DBSCAN observation whose specified-radius neighborhood contains at least the required minimum number of observations, including itself.

How 2 Manning books explain it

Advanced Algorithms and Data Structures

A core point in DBSCAN is a data point whose neighborhood contains at least the required number of dataset points within the specified radius.

How it is used
Uses core points to decide which DBSCAN points expand clusters and which nearby points merely join them.
How deep it goes
Defines the neighborhood threshold, develops the expansion rule, and relates its range-query implementation to conditional running-time bounds.
Examples
Illustrates a minPoints threshold of 3, a DBSCAN expansion loop, and border-point handling across adjacent shards.
What you can do after
Build it from scratch by counting ε-neighbors, expanding only from core points, and checking shard margins when distributing DBSCAN.

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Data Without Labels

A core point is a DBSCAN observation having at least minPts points, including itself, within epsilon distance.

How it is used
Uses local point density to identify the building blocks of DBSCAN clusters.
How deep it goes
Defines the ε and minPts test and links it to density, but does not detail the full clustering procedure.
Examples
Illustrates core points with Figure 2.29 and DBSCAN configurations using alternative eps and min_samples values.
What you can do after
Evaluate whether observations satisfy a DBSCAN neighborhood density threshold.

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Related concepts

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