The space join of a topological space 
and a point 
,
.
Space Cone
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References
Rolfsen, D. Knots and Links. Wilmington, DE: Publish or Perish Press, p. 6, 1976.Referenced on Wolfram|Alpha
Space ConeCite this as:
Weisstein, Eric W. "Space Cone." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/SpaceCone.html