solve does not take positive=True into account

[retsyo]

I am using sympy 1.12 with python-3.10.9.amd64 on windows 10 64bits

Given $s=\LARGE \frac {50} {r+1}$, if $r \geq 0$ then we know that if $r<49$, in a all, $0 \leq r<49$, then $s>1$.

I try to solve it by

import sys
from sympy import *

r = Symbol('r', positive=True)

s = 50/(r+1)

x0 = solve(f'{s}>1')
print(f'{x0}')

which says

(-1 < r) & (r < 49)

in other words, solve does not find that r is a positive number to give an corrected answer as (0 <= r) & (r < 49)

[oscarbenjamin]

It is a mistake that solve pretends to check assumptions when it cannot do it properly. Also solve should be changed to not "solve" inequalities like this as it is incompatible with what solve otherwise does. There should be a separate function for "solving" inequalities (actually there are several but none of them really works very well for a system of inequalities).

[oscarbenjamin]

The function that should be used here is reduce_inequalities but it needs improvement:

In [23]: reduce_inequalities([(50/(x+1) > 1), (x > 0)])
Out[23]: -1 < x ∧ 0 < x ∧ x < 49 ∧ x < ∞

[retsyo]

>>> from sympy import *
>>> __version__
'1.12'
>>> x = Symbol('x')
>>> reduce_inequalities([(50/(x+1) > 1), (x > 0)])
(-1 < x) & (0 < x) & (x < 49) & (x < oo)
>>> reduce_inequalities([(50/(x+1) > 1)])
(-1 < x) & (x < 49)

but if we tell that the symbol is positive

>>> y = Symbol('y', positive=True)
>>> reduce_inequalities([(50/(y+1) > 1), (y > 0)])
y < 49
>>> reduce_inequalities([(50/(y+1) > 1)])
y < 49

which I think the answer shoule be

(0<y) & (y < 49)