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! operator


Hi,

Could you explain a mysterious behaviour of "! operator" as shown below?


In[43]:=
MemberQ[{1,2,3},3]

Out[43]=
True

In[47]:=
!MemberQ[{1,2,3},3]
(*  Here Mathematica does not give any response!  *)

In[48]:=
Not@MemberQ[{1,2,3},3]

Out[48]=
False


Considering the description from Mathematica help:
	"!expr is the logical NOT function. It gives False if expr is True,
and True if it is False."
This behaviour seems quite suspicious?


DongGook


---------------------------------- 
DongGook Park, 
School of Information Technology, 
SunChon University, Korea 
Telephone:  +82 61 750 3597 
Mobile:  +82 18 732 2125 
Home page:  http://www.dgpark6.com/
Email:  dgpark6 at sunchon.ac.kr



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