
#1
Sep2610, 12:32 PM

P: 3,843

I don't know the meaning of these:
1) [tex]sup_{B_\delta}f(x,y) [/tex] Where [itex]B_\delta [/itex] is the ball of radius [itex]\delta[/itex]. 2) [tex]\int \int _{R^2 \B _{\delta} } f(xy)dxdy[/tex] I don't know what is [itex]R^2 [/itex]\B[itex] _{\delta} [/itex] Please read my latex because the symbol really don't show correctly. 



#2
Sep2610, 03:06 PM

Sci Advisor
P: 905

1) The supremum of {f(x,y)} where (x,y) ranges over the ball centered at 0 of radius delta: (x,y)=sqrt(x^2+y^2)<delta.
2) the plane R^2 without the ball centered at 0 of radius delta, i.e. \ (in Latex: "\backslash") means 'complement' or 'set difference'. So it consists of pairs (x,y) of real numbers such that (x,y)=sqrt(x^2+y^2)>=delta. 



#3
Sep2710, 12:20 AM

P: 3,843

1) Is the upper bound of f(x,y) in the ball. 2) Is the whole 2D plane minus the circle center at 0 with radius [itex]\delta[/itex] 



#4
Sep2710, 06:43 AM

Sci Advisor
P: 905

Question on meaning of some symbols 



#5
Sep2710, 08:09 AM

Math
Emeritus
Sci Advisor
Thanks
PF Gold
P: 38,886




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