That are used only for propagation

         But the approach seems not scalable

They are not all equal to zero

      Add divisible and is_int

       dolmen: c47a8109851cd4a0b14c8e45124330d3d08154d9

    Was doing the inverse

[Quant] Substitute by prefering existing terms to new equal one

See merge request !25

    since 0 added to sign

      It is complicated to know who is responsible for this choice

       same for ceiling, floor, floor_to_int