G is now talking about locally compact spaces and there are two phrases I have not seen. One is "relatively compact". I assume this is the same as what I call "conditionally compact", i.e. having compact closure. The other is "denombrable". The context is "Suppose that the locally compact space $X$ is denombrable a l'infini". Does it mean first countable? I don't want to start a discussion what bad terms these are, I just want to know what they mean. Michael
These are Bourbaki terms. Denombrable: countable denombrable a l'infini: countable at infinity (the point at infinity of the Alexandroff compactification of a locally compact space has a countable neighborhood base) relativement compact: relatively compact (having compact closure) Johannes
G is now talking about locally compact spaces and there are two phrases I have not seen. One is "relatively compact". I assume this is the same as what I call "conditionally compact", i.e. having compact closure. The other is "denombrable". The context is "Suppose that the locally compact space $X$ is denombrable a l'infini". Does it mean first countable?
I don't want to start a discussion what bad terms these are, I just want to know what they mean.
Michael
Michael Barr wrote in part:
G is now talking about locally compact spaces and there are two phrases I have not seen. One is "relatively compact". I assume this is the same as what I call "conditionally compact", i.e. having compact closure.
Depending on the author, "relatively compact" can mean either having compact closure, or having *any* compact superset. In a Hausdorff space, these are equivalent. --Toby
participants (3)
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Johannes.Huebschmann@math.univ-lille1.fr -
Michael Barr -
Toby Bartels