Open

In topology, the term "open" refers to an open set. The opposite of open is closed.

When referring to a problem, conjecture, etc. "open" means unsolved or unproven.

See also

Closed, Closed Set, Open Interval, Open Manifold, Open Map, Open Set, Unsolved Problems

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Cite this as:

Weisstein, Eric W. "Open." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Open.html

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