bag intersection definition

#1

The "standard" definition when

{1,1,1} intersect {1,1} = {1,1}

is just plain naive. Given that

intersection = projection * equality selection * cross product

(operator multiplication notation is right-associate)

the definition should be:

{1,1,1} intersect {1,1} = {1,1,1,1,1,1}

#2

Mikito Harakiri wrote:

Quote:

The "standard" definition when

{1,1,1} intersect {1,1} = {1,1}

is just plain naive. Given that

intersection = projection * equality selection * cross product

(operator multiplication notation is right-associate)

the definition should be:

{1,1,1} intersect {1,1} = {1,1,1,1,1,1}

Yeah, but then you lose the equation that X intersect X = X. Anyway, this is
largely esthetics.

-- Jan Hidders

#3

"Jan Hidders" <jan.hidders (AT) pandora (DOT) be> wrote

Quote:

{1,1,1} intersect {1,1} = {1,1,1,1,1,1}

Yeah, but then you lose the equation that X intersect X = X. Anyway, this
is
largely esthetics.

X union X = X

is not valid for bags either. Dual operations must have (or must have not)
dual identities.

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bag intersection definition

comp.databases.theory comp.databases.theory

bag intersection definition - 09-05-2003 , 07:40 PM

Re: bag intersection definition - 09-09-2003 , 04:03 PM

Re: bag intersection definition - 09-09-2003 , 04:33 PM