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Pushoam
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Is a surface bounding a volume always a closed surface?
It is a closed manifold. It is not a compact manifold, but as the boundary of a bounding submanifold it is closed. Each neighborhood of ##\{x=0\}## contains points with ##x=0## and ##x > 0## so it's a boundary and boundaries are closed. Considered as manifold in its own right, it is trivially closed.zwierz said:The set ##\{(x,y)\in\mathbb{R}^2\mid x\ge 0\}## has a boundary ##\{x=0\}##. This boundary is a closed subset of the plane but it is not a closed manifold
this does not meet the standard definition:fresh_42 said:It is a closed manifold. It is not a compact manifold
I just have shown that there is a standard meaning of the term "closed manifold". This meaning is broadly used regardless of your disagreement.fresh_42 said:So what?
A closed surface is a three-dimensional shape that completely encloses a space or volume. It has no holes or gaps and is considered a continuous surface with no edges or boundaries.
To bound a volume means to enclose or surround it with a physical barrier or boundary. In the context of a closed surface, it means to completely enclose the space or volume inside the surface, creating a solid object.
A closed surface is important because it allows for the calculation and measurement of the volume within it. Without a closed surface, it is impossible to accurately determine the volume of a space or object.
A closed surface and a volume are closely related, as the surface completely surrounds and encloses the volume. The surface is essentially the boundary that defines the volume and allows for its measurement and calculation.
A closed surface is used in various fields of science, such as physics, engineering, and mathematics, to determine the volume of objects or spaces. It is also used in computer graphics and modeling to create three-dimensional objects with defined boundaries.