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https://issues.apache.org/jira/browse/GEOMETRY-94?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17090471#comment-17090471
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Gilles Sadowski commented on GEOMETRY-94:
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{quote}"sub" is a standard convention in geometry. The terms "space" and
"subspace" follow that convention as well as "hyperplane" and "sub-hyperplane"
{quote}
A "subspace" is a "space" (of lower dimension).
A "hyperplane" of a n-dimensional "space" is a "space" with n-1 dimensions.
A
[{{SubHyperplane}}|https://gitbox.apache.org/repos/asf?p=commons-geometry.git;a=blob;f=commons-geometry-core/src/main/java/org/apache/commons/geometry/core/partitioning/SubHyperplane.java;h=74a416937362b9cd8f92c0905fcb619161b5cd8c;hb=HEAD]
is not a "space".
{quote}when I see the word "set" at the end of that class name [...]
{quote}
I know I may sound like nit-picking, but so you are here. ;)
{{HyperplaneConvexSubset}} would accurately indicate a collection (indeed!) of
parts of a hyperplane;
while my point above is that "sub" is used with two completely different
meanings.
{quote}ConvexSubHyperplane implies a more mathematically defined structure.
{quote}
It seems so indeed; that's why I was looking for a reference to that term; and
[there is
one|https://www.google.com/search?q=convex+sub+hyperplane&sxsrf=ALeKk01zhi9vQdbEr_uBpS_GBlzYm07R8g:1587635112537&ei=qGOhXu-lIIu-kwWmsr_gCQ&start=10&sa=N&ved=2ahUKEwjvmanXof7oAhUL36QKHSbZD5wQ8NMDegQIDRA_&biw=1238&bih=499]:
In a book that introduces it within the context of "BSP-Tree"!
So I should perhaps rephrase: Confusion comes from a term that seemingly looks
like it is a "mathematical structure" while it was perhaps coined with an
explicit eye to programming (geometrical modeling).
So let's say that we stick with this usage. However, to avoid further
wondering and sterile web searches about "What is a subhyperplane?", I'd
suggest that the userguide and Javadoc don't use "subhyperplane" as if it were
a concept defined in geometry. For example, in the Javadoc of
[{{SubHyperplane}}|https://gitbox.apache.org/repos/asf?p=commons-geometry.git;a=blob;f=commons-geometry-core/src/main/java/org/apache/commons/geometry/core/partitioning/SubHyperplane.java;h=74a416937362b9cd8f92c0905fcb619161b5cd8c;hb=HEAD],
the word could always be written as
{noformat}
{@code SubHyperplane}
{noformat}
It may again sound as nit-picking, but (IMHO at least), it could be an
important hint to avoid drawing meaningless conclusions (about the meaning of
"sub").
> ConvexSubPlane Subclasses
> -------------------------
>
> Key: GEOMETRY-94
> URL: https://issues.apache.org/jira/browse/GEOMETRY-94
> Project: Apache Commons Geometry
> Issue Type: New Feature
> Reporter: Matt Juntunen
> Priority: Major
> Labels: beta1
>
> There should be specific subclasses of {{ConvexSubPlane}} to allow for
> optimization and ease of use.
> - {{OpenConvexSubPlane}} - extends {{ConvexSubPlane}}; represents a convex
> subplane that is open on a least one side and has infinite size
> - {{ClosedConvexSubPlane}} - extends {{ConvexSubPlane}}; represents a convex
> subplane with finite size; the 2D subspace is a polygon
> - {{Triangle3D}} - extends {{ClosedConvexSubPlane}}; represents a triangle
> in 3D space; most 3D models are or can easily be represented with triangles
> so it would be good to have a dedicated class for this.
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