Universal Property for Field of Quotients

From ProofWiki
Jump to navigation Jump to search

Theorem

Let $\struct {D, +, \circ}$ be an integral domain.

Let $\struct {F, \oplus, \cdot}$ be a field of quotients of $D$.


Then $F$ satisfies the following universal property:

There exists a (ring) homomorphism $\iota : D \to F$ such that:

for every field $\tilde F$ and
and:
for every (ring) homomorphism $\phi: D \to \tilde F$
there exists a unique field homomorphism $\psi: F \to \tilde F$ satisfying:
$\psi \iota = \phi$


That is, the following diagram commutes:

Universal Property



Namely we may take:

$\psi: a / b \mapsto \map \phi a \map \phi b^{-1}$


Proof