A certain problem has the following domains:

X >= 2 and Y >4.5
X >= 2 and Y <=4.5
X < 2 and Y > 4.5
X < 2 and Y <=4.5
1) Identify the Open and Closed Domains.
2) What points should be tested? Each point is defined by an X-value
and a Y-value as for example (X = 1, Y = 7). If the point is not
uniquely defined, you can use an example. For instance, if you want a
point with an X-value slightly greater than 0, you could use X = 0.1

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Request for Question Clarification by mathtalk-ga on 02 Mar 2003 17:16 PST

Hi, mohd_fm-ga:

What kind of class were these problem posed in?  Often the first
mention of "open" and "closed" sets occurs, with respect to intervals,
in high school algebra.  Later the same distinction is used
substantively in first year calculus.

Here the sets ("domains") appear to be subsets of the Cartesian plane
rather than intervals.  The definitions might be given, with varying
emphasis on detail, in a) a second year calculus class, b) an
undergraduate real analysis class, or c) a topology class.

It would help me or another researcher to provide an explanation at
the right level of discussion if we knew more about the context of
your question.

Thanks,
mathtalk-ga