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Paul Taylor
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Yes.

First note that Galois connections are far more common than field theorists would have you believe: any binary relation gives rise to one and the two fixed sets a closed under any appropriate algebraic structure.

Write

  • $P\perp Q$ for "every member of $P$ is orthogonal (in the sense of factorisation systems) to every member of $Q$";

  • $P;Q$ for the set of all composites of members of $P$ followed by members of $Q$;

  • $L'=L\cap E_0\cap M_1$ and $R'=R\cap E_0\cap M_1$ (to avoid any ambiguity in this argument); and

  • $E=E_1;L'$ and $M=R';M_0$.

Then

  • $E_1\perp M_1\supset R'$,

  • $E_1\perp M_1\supset M_0$,

  • $L'\subset L\perp R\supset R'$ and

  • $L'\subset E_0\perp M_0$.

Since orthogonality respects composition, it follows that $E\perp M$, whilst by construction $E;M$ is the entire hom-class of the category.

Therefore $(E,M)$ is a factorisation system.

The things that I have assumed are all proved in my book but I don't have a copy to hand to look up the references.

In the question as stated, it is given that $M_0\subset M_1$, but there is no order-relationship between these and $R$. This is why it was necessary to introduce $R'$. The construction gives a way of handling expressions in the lattice of factorisation systems on a category, so it would be an interesting exercise in lattice theory to find out whether this is modular or even distributive.

Yes.

First note that Galois connections are far more common than field theorists would have you believe: any binary relation gives rise to one and the two fixed sets a closed under any appropriate algebraic structure.

Write

  • $P\perp Q$ for "every member of $P$ is orthogonal (in the sense of factorisation systems) to every member of $Q$";

  • $P;Q$ for the set of all composites of members of $P$ followed by members of $Q$;

  • $L'=L\cap E_0\cap M_1$ and $R'=R\cap E_0\cap M_1$ (to avoid any ambiguity in this argument); and

  • $E=E_1;L'$ and $M=R';M_0$.

Then

  • $E_1\perp M_1\supset R'$,

  • $E_1\perp M_1\supset M_0$,

  • $L'\subset L\perp R\supset R'$ and

  • $L'\subset E_0\perp M_0$.

Since orthogonality respects composition, it follows that $E\perp M$, whilst by construction $E;M$ is the entire hom-class of the category.

Therefore $(E,M)$ is a factorisation system.

The things that I have assumed are all proved in my book but I don't have a copy to hand to look up the references.

Yes.

First note that Galois connections are far more common than field theorists would have you believe: any binary relation gives rise to one and the two fixed sets a closed under any appropriate algebraic structure.

Write

  • $P\perp Q$ for "every member of $P$ is orthogonal (in the sense of factorisation systems) to every member of $Q$";

  • $P;Q$ for the set of all composites of members of $P$ followed by members of $Q$;

  • $L'=L\cap E_0\cap M_1$ and $R'=R\cap E_0\cap M_1$ (to avoid any ambiguity in this argument); and

  • $E=E_1;L'$ and $M=R';M_0$.

Then

  • $E_1\perp M_1\supset R'$,

  • $E_1\perp M_1\supset M_0$,

  • $L'\subset L\perp R\supset R'$ and

  • $L'\subset E_0\perp M_0$.

Since orthogonality respects composition, it follows that $E\perp M$, whilst by construction $E;M$ is the entire hom-class of the category.

Therefore $(E,M)$ is a factorisation system.

The things that I have assumed are all proved in my book but I don't have a copy to hand to look up the references.

In the question as stated, it is given that $M_0\subset M_1$, but there is no order-relationship between these and $R$. This is why it was necessary to introduce $R'$. The construction gives a way of handling expressions in the lattice of factorisation systems on a category, so it would be an interesting exercise in lattice theory to find out whether this is modular or even distributive.

added 46 characters in body
Source Link
Paul Taylor
  • 8.5k
  • 1
  • 29
  • 58

Yes.

First note that Galois connections are far more common than field theorists would have you believe: any binary relation gives rise to one and the two fixed sets a closed under any appropriate algebraic structure.

Write

  • $P\perp Q$ for "every member of $P$ is orthogonal (in the sense of factorisation systems) to every member of $Q$";

  • $P;Q$ for the set of all composites of members of $P$ followed by members of $Q$;

  • $L'=L\cap E_0\cap M_1$ and $R'=R\cap E_0\cap M_1$. (to avoid any ambiguity in this argument); and

  • $E=E_1;L'$ and $M=R';M_0$.

Then

  • $E_1\perp M_1\supset R'$,

  • $E_1\perp M_1\supset M_0$,

  • $L'\subset L\perp R\supset R'$ and

  • $L'\subset E_0\perp M_0$.

Since orthogonality respects composition, it follows that $E\perp M$, whilst by construction $E;M$ is the entire hom-class of the category.

Therefore $(E,M)$ is a factorisation system.

The things that I have assumed are all proved in my book but I don't have a copy to hand to look up the references.

Yes.

First note that Galois connections are far more common than field theorists would have you believe: any binary relation gives rise to one and the two fixed sets a closed under any appropriate algebraic structure.

Write

  • $P\perp Q$ for "every member of $P$ is orthogonal (in the sense of factorisation systems) to every member of $Q$";

  • $P;Q$ for the set of all composites of members of $P$ followed by members of $Q$;

  • $L'=L\cap E_0\cap M_1$ and $R'=R\cap E_0\cap M_1$.

  • $E=E_1;L'$ and $M=R';M_0$.

Then

  • $E_1\perp M_1\supset R'$,

  • $E_1\perp M_1\supset M_0$,

  • $L'\subset L\perp R\supset R'$ and

  • $L'\subset E_0\perp M_0$.

Since orthogonality respects composition, it follows that $E\perp M$, whilst by construction $E;M$ is the entire hom-class of the category.

Therefore $(E,M)$ is a factorisation system.

The things that I have assumed are all proved in my book but I don't have a copy to hand to look up the references.

Yes.

First note that Galois connections are far more common than field theorists would have you believe: any binary relation gives rise to one and the two fixed sets a closed under any appropriate algebraic structure.

Write

  • $P\perp Q$ for "every member of $P$ is orthogonal (in the sense of factorisation systems) to every member of $Q$";

  • $P;Q$ for the set of all composites of members of $P$ followed by members of $Q$;

  • $L'=L\cap E_0\cap M_1$ and $R'=R\cap E_0\cap M_1$ (to avoid any ambiguity in this argument); and

  • $E=E_1;L'$ and $M=R';M_0$.

Then

  • $E_1\perp M_1\supset R'$,

  • $E_1\perp M_1\supset M_0$,

  • $L'\subset L\perp R\supset R'$ and

  • $L'\subset E_0\perp M_0$.

Since orthogonality respects composition, it follows that $E\perp M$, whilst by construction $E;M$ is the entire hom-class of the category.

Therefore $(E,M)$ is a factorisation system.

The things that I have assumed are all proved in my book but I don't have a copy to hand to look up the references.

added 71 characters in body
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Paul Taylor
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  • 1
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  • 58

Yes.

First note that Galois connections are far more common than field theorists would have you believe: any binary relation gives rise to one and the two fixed sets a closed under any appropriate algebraic structure.

Write

  • $P\perp Q$ for "every member of $P$ is orthogonal (in the sense of factorisation systems) to every member of $Q$";

  • $P;Q$ for the set of all composites of members of $P$ followed by members of $Q$;

  • $L'=L\cap E_0\cap M_1$ and $R'=R\cap E_0\cap M_1$.

  • $E=E_1;L'$ and $M=R';M_0$.

Then

  • $E_1\perp M_1\supset R'$,

  • $E_1\subset E_0\perp M_0$$E_1\perp M_1\supset M_0$,

  • $L'\subset L\perp R\supset R'$ and

  • $L'\subset E_0\perp M_0$,.

soSince orthogonality respects composition, it follows that $E\perp M$, whilst by construction $E;M$ is the entire hom-class of the category.

Therefore $(E,M)$ is a factorisation system.

The things that I have assumed are all proved in my book but I don't have a copy to hand to look up the references.

Yes.

First note that Galois connections are far more common than field theorists would have you believe: any binary relation gives rise to one and the two fixed sets a closed under any appropriate algebraic structure.

Write

  • $P\perp Q$ for "every member of $P$ is orthogonal (in the sense of factorisation systems) to every member of $Q$";

  • $P;Q$ for the set of all composites of members of $P$ followed by members of $Q$;

  • $L'=L\cap E_0\cap M_1$ and $R'=R\cap E_0\cap M_1$.

  • $E=E_1;L'$ and $M=R';M_0$.

Then

  • $E_1\perp M_1\supset R'$,

  • $E_1\subset E_0\perp M_0$,

  • $L'\subset L\perp R\supset R'$ and

  • $L'\subset E_0\perp M_0$,

so $E\perp M$, whilst $E;M$ is the entire hom-class of the category.

Therefore $(E,M)$ is a factorisation system.

The things that I have assumed are all proved in my book but I don't have a copy to hand to look up the references.

Yes.

First note that Galois connections are far more common than field theorists would have you believe: any binary relation gives rise to one and the two fixed sets a closed under any appropriate algebraic structure.

Write

  • $P\perp Q$ for "every member of $P$ is orthogonal (in the sense of factorisation systems) to every member of $Q$";

  • $P;Q$ for the set of all composites of members of $P$ followed by members of $Q$;

  • $L'=L\cap E_0\cap M_1$ and $R'=R\cap E_0\cap M_1$.

  • $E=E_1;L'$ and $M=R';M_0$.

Then

  • $E_1\perp M_1\supset R'$,

  • $E_1\perp M_1\supset M_0$,

  • $L'\subset L\perp R\supset R'$ and

  • $L'\subset E_0\perp M_0$.

Since orthogonality respects composition, it follows that $E\perp M$, whilst by construction $E;M$ is the entire hom-class of the category.

Therefore $(E,M)$ is a factorisation system.

The things that I have assumed are all proved in my book but I don't have a copy to hand to look up the references.

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