Parsing double inequalities

[nikos-kekatos]

In the platooning benchmark, the parsing induces the following error:

invariant -9 <= aL <= 1 in location 1 not understood

[schillic]

Just a guess: You need to split double inequalities a <= x <= b into a <= x & x <= b.

[mforets]

At least parsing the string works as expected:

julia> SX.parse_sxmath("-1 <= x <= 1")
1-element Array{Expr,1}:
 :(-1 <= x <= 1)

[mforets]

Just a guess: You need to split double inequalities a <= x <= b into a <= x & x <= b.

Yes, i think your guess is correct. This type of expression is a :comparison and it was not been taken into account for the transformation of expressions to sets.

julia> using SX

julia> expr = SX.parse_sxmath("-9 <= aL <= 9")
1-element Array{Expr,1}:
 :(-9 <= aL <= 9)

julia> expr[1].head
:comparison

julia> expr[1].args
5-element Array{Any,1}:
 -9
   :(<=)
   :aL
   :(<=)
  9

It is easy to add a new case, checking that the args 2 and 4 are <= and then transform it into two halfspaces.

[mforets]

Another model with uses this conjunction notation is the linear switching SX model.