Mixing
What does this symbol mean in commutative algebra?
$begingroup$
(Algebraic Geometry and commutative algebra - Bosch - page 16)
I could not find the symbol in the glossary at the end of the book. What does it mean ?
I cannot see it in my reference manual either (Commutative Algebra with a view towards algebraic geometry - Eisenbud)
elementary-set-theory commutative-algebra
asked Jan 12 at 9:35
user3203476user3203476
746613
$endgroup$
add a comment |
$begingroup$
(Algebraic Geometry and commutative algebra - Bosch - page 16)
I could not find the symbol in the glossary at the end of the book. What does it mean ?
I cannot see it in my reference manual either (Commutative Algebra with a view towards algebraic geometry - Eisenbud)
elementary-set-theory commutative-algebra
asked Jan 12 at 9:35
user3203476user3203476
746613
$endgroup$
2
$begingroup$
I suspect the symbol denotes a coproduct.
$endgroup$
– drhab
Jan 12 at 9:42
1
$begingroup$
As for the latex-symbol, see here.
$endgroup$
– Dietrich Burde
Jan 12 at 9:48
add a comment |
$begingroup$
(Algebraic Geometry and commutative algebra - Bosch - page 16)
I could not find the symbol in the glossary at the end of the book. What does it mean ?
I cannot see it in my reference manual either (Commutative Algebra with a view towards algebraic geometry - Eisenbud)
elementary-set-theory commutative-algebra
asked Jan 12 at 9:35
user3203476user3203476
746613
$endgroup$
(Algebraic Geometry and commutative algebra - Bosch - page 16)
I could not find the symbol in the glossary at the end of the book. What does it mean ?
I cannot see it in my reference manual either (Commutative Algebra with a view towards algebraic geometry - Eisenbud)
elementary-set-theory commutative-algebra
elementary-set-theory commutative-algebra
asked Jan 12 at 9:35
user3203476user3203476
746613
asked Jan 12 at 9:35
user3203476user3203476
746613
asked Jan 12 at 9:35
user3203476user3203476
746613
asked Jan 12 at 9:35
user3203476user3203476
746613
asked Jan 12 at 9:35
user3203476user3203476
746613
746613
2
$begingroup$
I suspect the symbol denotes a coproduct.
$endgroup$
– drhab
Jan 12 at 9:42
1
$begingroup$
As for the latex-symbol, see here.
$endgroup$
– Dietrich Burde
Jan 12 at 9:48
add a comment |
2
$begingroup$
I suspect the symbol denotes a coproduct.
$endgroup$
– drhab
Jan 12 at 9:42
1
$begingroup$
As for the latex-symbol, see here.
$endgroup$
– Dietrich Burde
Jan 12 at 9:48
2
2
$begingroup$
I suspect the symbol denotes a coproduct.
$endgroup$
– drhab
Jan 12 at 9:42
$begingroup$
I suspect the symbol denotes a coproduct.
$endgroup$
– drhab
Jan 12 at 9:42
1
1
$begingroup$
As for the latex-symbol, see here.
$endgroup$
– Dietrich Burde
Jan 12 at 9:48
$begingroup$
As for the latex-symbol, see here.
$endgroup$
– Dietrich Burde
Jan 12 at 9:48
add a comment |
1 Answer
1
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oldest
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$begingroup$
Its the disjoint union from set theory. Each element of $text{Spec } R$ maps into a different set from the disjoint union.
In category theory this symbol can sometimes be a coproduct, but in this situation it’s not.
Added: Of course disjoint union is the coprduct in sets, but you hardly see all those rings/ $R$-modules and think “category of sets”. This tradition of confusing young scholars of scheme theory goes back, at least to Hartshorne’s book.
answered Jan 12 at 9:45
BenBen
3,756616
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$begingroup$
Its the disjoint union from set theory. Each element of $text{Spec } R$ maps into a different set from the disjoint union.
In category theory this symbol can sometimes be a coproduct, but in this situation it’s not.
Added: Of course disjoint union is the coprduct in sets, but you hardly see all those rings/ $R$-modules and think “category of sets”. This tradition of confusing young scholars of scheme theory goes back, at least to Hartshorne’s book.
answered Jan 12 at 9:45
BenBen
3,756616
$endgroup$
add a comment |
$begingroup$
Its the disjoint union from set theory. Each element of $text{Spec } R$ maps into a different set from the disjoint union.
In category theory this symbol can sometimes be a coproduct, but in this situation it’s not.
Added: Of course disjoint union is the coprduct in sets, but you hardly see all those rings/ $R$-modules and think “category of sets”. This tradition of confusing young scholars of scheme theory goes back, at least to Hartshorne’s book.
answered Jan 12 at 9:45
BenBen
3,756616
$endgroup$
add a comment |
$begingroup$
Its the disjoint union from set theory. Each element of $text{Spec } R$ maps into a different set from the disjoint union.
In category theory this symbol can sometimes be a coproduct, but in this situation it’s not.
Added: Of course disjoint union is the coprduct in sets, but you hardly see all those rings/ $R$-modules and think “category of sets”. This tradition of confusing young scholars of scheme theory goes back, at least to Hartshorne’s book.
answered Jan 12 at 9:45
BenBen
3,756616
$endgroup$
Its the disjoint union from set theory. Each element of $text{Spec } R$ maps into a different set from the disjoint union.
In category theory this symbol can sometimes be a coproduct, but in this situation it’s not.
Added: Of course disjoint union is the coprduct in sets, but you hardly see all those rings/ $R$-modules and think “category of sets”. This tradition of confusing young scholars of scheme theory goes back, at least to Hartshorne’s book.
answered Jan 12 at 9:45
BenBen
3,756616
edited Jan 12 at 9:53
answered Jan 12 at 9:45
BenBen
3,756616
answered Jan 12 at 9:45
BenBen
3,756616
answered Jan 12 at 9:45
BenBen
3,756616
3,756616
add a comment |
add a comment |
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2
$begingroup$
I suspect the symbol denotes a coproduct.
$endgroup$
– drhab
Jan 12 at 9:42
1
$begingroup$
As for the latex-symbol, see here.
$endgroup$
– Dietrich Burde
Jan 12 at 9:48