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Negative implications for properties

Need:
1
 Time:
-
Component: Method selection
Contact: max.neunhoeffer@math.rwth-aachen.de
Last Update: 1999/3/9
Math:
-
 Program:
-

Description

If for example a group knows not to be nilpotent at present it tells that it does not know whether it is abelian or cyclic. Of course it could know that it is not abelian and not cyclic. Also if that group is in fact a subgroup of another one it does not know if it is central in the bigger group which again of course it could know.

The general problem is that certain properties imply others but that having not a certain property does not imply anything in the other direction.

We noticed this by looking at the information menus for subgroups in X GAP , where for the user it looks of course rather silly to read

IsAbelian Unknown
IsCyclic Unknown
IsCentral Unknown
IsNilpotent false

Remarks

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