Hi all,

Cutting to the chase, I realized that the modulo operator "%" is 
un-naturally defined to be constant-zero in the fraction field of 
polynomials. This has caused the following issue.

See the following minimal code on the online Sage server: Sage Cell Server 
<https://sagecell.sagemath.org/?z=eJwLUrBVCAyMrojl5aoAMoM0KjR5udKBLI2KOCNdQ019jQogyctVUJSZV6IRpGGoqZquCQBWrwzG&lang=sage&interacts=eJyLjgUAARUAuQ==>

In this example, we are doing 1 modulo x+1, which supposedly should give us 
1 as output. However, since the datatype of x+1 is rational polynomial, it 
produces 0 as output.

I imagine there are two ways that may potentially solve this issue:
(1) Disgard the modulo operator % for fraction field! In the mathematical 
sense there is no interesting modulo (other than producing zero) for 
fraction field anyway, so such an operator seems more confusing than 
helpful. Removing % from fraction field should also cause the triggering of 
coersion from rational polynomial to a polynomial in the above example.
(2) Perform the modulo only on the integral ideal. Upon each time we 
compute f%g in a fraction field, we can derive its ring of integer O, and, 
return a representative in the co-set f + g*O. In the above example, this 
should also return the representative 1.

Best,
Yu-Hsuan (Taylor)

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