About GLPK.exact it is not possible to get the rational number 3/28 instead > of a decimal approximation ? >
No, unfortunately. Also, for that to happen/make sense, you'd also need to be able to pass all the *inputs* as exact rational values, i.e. as "1//7" instead of "1/7". This would be possible if we had a native generic Julia linear programming solver, but it's not possible with GLPK, which can only use exact arithmetic internally.
