Merge pull request #779 from JuliaReach/rip_upper_bound

RIP upper_bound

docs/src/lib/approximations.md

@@ -66,9 +66,3 @@ BoxDiagDirections
 ```
 
 See also `overapproximate(X::LazySet, dir::AbstractDirections)::HPolytope`.
-
-## Upper bounds
-
-```@docs
-ρ_upper_bound
-```

src/Approximations/Approximations.jl

@@ -37,6 +37,5 @@ include("box_approximations.jl")
 include("template_directions.jl")
 include("overapproximate.jl")
 include("decompositions.jl")
-include("upper_bounds.jl")
 
 end # module

src/Approximations/box_approximations.jl

@@ -3,15 +3,13 @@
 # ===================================
 
 """
-    box_approximation(S::LazySet; upper_bound::Bool=false)::Hyperrectangle
+    box_approximation(S::LazySet)::Hyperrectangle
 
 Overapproximate a convex set by a tight hyperrectangle.
 
 ### Input
 
 - `S`           -- convex set
-- `upper_bound` -- (optional, default: `false`) use overapproximation in support
-                   function computation?
 
 ### Output
 
@@ -24,20 +22,19 @@ of the given set in the canonical directions, and the lengths of the sides can
 be recovered from the distance among support functions in the same directions.
 """
 function box_approximation(S::LazySet{N};
-                           upper_bound::Bool=false
                           )::Union{Hyperrectangle{N}, EmptySet{N}} where N<:Real
-    (c, r) = box_approximation_helper(S; upper_bound=upper_bound)
-    if upper_bound && r[1] < 0
+    (c, r) = box_approximation_helper(S)
+    if r[1] < 0
         return EmptySet{N}()
     end
     return Hyperrectangle(c, r)
 end
 
 # special case: Hyperrectangle
-box_approximation(S::Hyperrectangle; upper_bound::Bool=false) = S
+box_approximation(S::Hyperrectangle) = S
 
 # special case: other rectangle
-box_approximation(S::AbstractHyperrectangle; upper_bound::Bool=false) =
+box_approximation(S::AbstractHyperrectangle) =
     Hyperrectangle(center(S), radius_hyperrectangle(S))
 
 """
@@ -48,7 +45,7 @@ Alias for `box_approximation`.
 interval_hull = box_approximation
 
 """
-    box_approximation_symmetric(S::LazySet{N}; upper_bound::Bool=false
+    box_approximation_symmetric(S::LazySet{N}
                                )::Union{Hyperrectangle{N}, EmptySet{N}}
                                 where {N<:Real}
 
@@ -57,8 +54,6 @@ Overapproximate a convex set by a tight hyperrectangle centered in the origin.
 ### Input
 
 - `S`           -- convex set
-- `upper_bound` -- (optional, default: `false`) use overapproximation in support
-                   function computation?
 
 ### Output
 
@@ -70,11 +65,10 @@ The center of the box is the origin, and the radius is obtained by computing the
 maximum value of the support function evaluated at the canonical directions.
 """
 function box_approximation_symmetric(S::LazySet{N};
-                                     upper_bound::Bool=false
                                     )::Union{Hyperrectangle{N},
                                              EmptySet{N}} where {N<:Real}
-    (c, r) = box_approximation_helper(S; upper_bound=upper_bound)
-    if upper_bound && r[1] < 0
+    (c, r) = box_approximation_helper(S)
+    if r[1] < 0
         return EmptySet{N}()
     end
     return Hyperrectangle(zeros(N, length(c)), abs.(c) .+ r)
@@ -88,16 +82,14 @@ Alias for `box_approximation_symmetric`.
 symmetric_interval_hull = box_approximation_symmetric
 
 """
-    box_approximation_helper(S::LazySet{N}; upper_bound::Bool=false
+    box_approximation_helper(S::LazySet{N};
                             ) where {N<:Real}
 
 Common code of `box_approximation` and `box_approximation_symmetric`.
 
 ### Input
 
 - `S`           -- convex set
-- `upper_bound` -- (optional, default: `false`) use overapproximation in support
-                   function computation?
 
 ### Output
 
@@ -115,24 +107,22 @@ The lengths of the sides can be recovered from the distance among support
 functions in the same directions.
 """
 @inline function box_approximation_helper(S::LazySet{N};
-                                          upper_bound::Bool=false
                                          ) where {N<:Real}
     zero_N = zero(N)
     one_N = one(N)
-    ρ_rec = upper_bound ? ρ_upper_bound : ρ
     n = dim(S)
     c = Vector{N}(undef, n)
     r = Vector{N}(undef, n)
     d = zeros(N, n)
     @inbounds for i in 1:n
         d[i] = one_N
-        htop = ρ_rec(d, S)
+        htop = ρ(d, S)
         d[i] = -one_N
-        hbottom = -ρ_rec(d, S)
+        hbottom = -ρ(d, S)
         d[i] = zero_N
         c[i] = (htop + hbottom) / 2
         r[i] = (htop - hbottom) / 2
-        if upper_bound && r[i] < 0
+        if r[i] < 0
             # contradicting bounds => set is empty
             # terminate with first radius entry being negative
             r[1] = r[i]
@@ -143,16 +133,14 @@ functions in the same directions.
 end
 
 """
-    ballinf_approximation(S::LazySet{N}; upper_bound::Bool=false
+    ballinf_approximation(S::LazySet{N};
                          )::BallInf{N} where {N<:Real}
 
 Overapproximate a convex set by a tight ball in the infinity norm.
 
 ### Input
 
 - `S`           -- convex set
-- `upper_bound` -- (optional, default: `false`) use overapproximation in support
-                   function computation?
 
 ### Output
 
@@ -164,26 +152,24 @@ The center and radius of the box are obtained by evaluating the support function
 of the given convex set along the canonical directions.
 """
 function ballinf_approximation(S::LazySet{N};
-                               upper_bound::Bool=false
                               )::Union{BallInf{N}, EmptySet{N}} where {N<:Real}
     zero_N = zero(N)
     one_N = one(N)
-    ρ_rec = upper_bound ? ρ_upper_bound : ρ
     n = dim(S)
     c = Vector{N}(undef, n)
     r = zero_N
     d = zeros(N, n)
     @inbounds for i in 1:n
         d[i] = one_N
-        htop = ρ_rec(d, S)
+        htop = ρ(d, S)
         d[i] = -one_N
-        hbottom = -ρ_rec(d, S)
+        hbottom = -ρ(d, S)
         d[i] = zero_N
         c[i] = (htop + hbottom) / 2
         rcur = (htop - hbottom) / 2
         if (rcur > r)
             r = rcur
-        elseif upper_bound && rcur < 0
+        elseif rcur < 0
             # contradicting bounds => set is empty
             return EmptySet{N}()
         end

src/Approximations/overapproximate.jl

@@ -30,16 +30,14 @@ Otherwise the result is an ε-close approximation as a polygon.
 - `S`           -- convex set, assumed to be two-dimensional
 - `HPolygon`    -- type for dispatch
 - `ε`           -- (optional, default: `Inf`) error bound
-- `upper_bound` -- (optional, default: `false`) currently ignored
 
 ### Output
 
 A polygon in constraint representation.
 """
 function overapproximate(S::LazySet{N},
                          ::Type{<:HPolygon},
-                         ε::Real=Inf;
-                         upper_bound::Bool=false
+                         ε::Real=Inf
                         )::HPolygon where {N<:Real}
     @assert dim(S) == 2
     if ε == Inf
@@ -59,15 +57,14 @@ function overapproximate(S::LazySet{N},
 end
 
 """
-    overapproximate(S::LazySet, ε::Real; [upper_bound]::Bool=false)::HPolygon
+    overapproximate(S::LazySet, ε::Real)::HPolygon
 
-Alias for `overapproximate(S, HPolygon, ε, upper_bound=upper_bound)`.
+Alias for `overapproximate(S, HPolygon, ε)`.
 """
 function overapproximate(S::LazySet,
                          ε::Real;
-                         upper_bound::Bool=false
                         )::HPolygon
-    return overapproximate(S, HPolygon, ε; upper_bound=upper_bound)
+    return overapproximate(S, HPolygon, ε)
 end
 
 """
@@ -80,18 +77,15 @@ Return an approximation of a given set as a hyperrectangle.
 
 - `S`              -- set
 - `Hyperrectangle` -- type for dispatch
-- `upper_bound`    -- (optional, default: `false`) use overapproximation in
-                      support function computation?
 
 ### Output
 
 A hyperrectangle.
 """
 function overapproximate(S::LazySet,
                          ::Type{<:Hyperrectangle};
-                         upper_bound::Bool=false
                         )::Union{Hyperrectangle, EmptySet}
-    box_approximation(S; upper_bound=upper_bound)
+    box_approximation(S)
 end
 
 """
@@ -100,22 +94,19 @@ end
 Alias for `overapproximate(S, Hyperrectangle)`.
 """
 overapproximate(S::LazySet;
-                upper_bound::Bool=false
                )::Union{Hyperrectangle, EmptySet} =
-    overapproximate(S, Hyperrectangle; upper_bound=upper_bound)
+    overapproximate(S, Hyperrectangle)
 
 """
     overapproximate(S::ConvexHull{N, Zonotope{N}, Zonotope{N}},
-                    ::Type{<:Zonotope};
-                    [upper_bound]::Bool=false)::Zonotope where {N<:Real}
+                    ::Type{<:Zonotope})::Zonotope where {N<:Real}
 
 Overapproximate the convex hull of two zonotopes.
 
 ### Input
 
 - `S`           -- convex hull of two zonotopes of the same order
 - `Zonotope`    -- type for dispatch
-- `upper_bound` -- (optional, default: `false`) currently ignored
 
 ### Algorithm
 
@@ -134,8 +125,7 @@ zonotope, which is in general expensive in high dimensions. This is further inve
 in: *Zonotopes as bounding volumes, L. J. Guibas et al, Proc. of Symposium on Discrete Algorithms, pp. 803-812*.
 """
 function overapproximate(S::ConvexHull{N, Zonotope{N}, Zonotope{N}},
-                         ::Type{<:Zonotope};
-                         upper_bound::Bool=false)::Zonotope where {N<:Real}
+                         ::Type{<:Zonotope})::Zonotope where {N<:Real}
     Z1, Z2 = S.X, S.Y
     @assert order(Z1) == order(Z2)
     center = (Z1.center+Z2.center)/2
@@ -145,8 +135,7 @@ end
 
 """
     overapproximate(X::LazySet,
-                    dir::AbstractDirections;
-                    [upper_bound]::Bool=false
+                    dir::AbstractDirections
                    )::HPolytope
 
 Overapproximating a set with template directions.
@@ -155,31 +144,26 @@ Overapproximating a set with template directions.
 
 - `X`           -- set
 - `dir`         -- direction representation
-- `upper_bound` -- (optional, default: `false`) use overapproximation in support
-                   function computation?
 
 ### Output
 
 A `HPolytope` overapproximating the set `X` with the directions from `dir`.
 """
 function overapproximate(X::LazySet{N},
                          dir::AbstractDirections{N};
-                         upper_bound::Bool=false
                         )::HPolytope{N} where N
-    ρ_rec = upper_bound ? ρ_upper_bound : ρ
     halfspaces = Vector{LinearConstraint{N}}()
     sizehint!(halfspaces, length(dir))
     H = HPolytope(halfspaces)
     for d in dir
-        addconstraint!(H, LinearConstraint(d, ρ_rec(d, X)))
+        addconstraint!(H, LinearConstraint(d, ρ(d, X)))
     end
     return H
 end
 
 """
     overapproximate(S::LazySet{N},
-                    ::Type{Interval};
-                    [upper_bound]::Bool=false
+                    ::Type{Interval}
                    ) where {N<:Real}
 
 Return the overapproximation of a real unidimensional set with an interval.
@@ -188,15 +172,13 @@ Return the overapproximation of a real unidimensional set with an interval.
 
 - `S`           -- one-dimensional set
 - `Interval`    -- type for dispatch
-- `upper_bound` -- (optional, default: `false`) currently ignored
 
 ### Output
 
 An interval.
 """
 function overapproximate(S::LazySet{N},
-                         ::Type{Interval};
-                         upper_bound::Bool=false
+                         ::Type{Interval}
                         ) where {N<:Real}
     @assert dim(S) == 1
     lo = σ([-one(N)], S)[1]
@@ -207,7 +189,6 @@ end
 """
     overapproximate(cap::Intersection{N, <:LazySet, S},
                     dir::AbstractDirections{N};
-                    [upper_bound]::Bool=false,
                     kwargs...
                    ) where {N<:Real, S<:AbstractPolytope{N}}
 
@@ -218,8 +199,6 @@ polytope given a set of template directions.
 
 - `cap`         -- intersection of a compact set and a polytope
 - `dir`         -- template directions
-- `upper_bound` -- (optional, default: `false`) use overapproximation in support
-                   function computation?
 - `kwargs`      -- additional arguments that are passed to the support function
                    algorithm
 
@@ -253,7 +232,6 @@ intersection is empty.
 """
 function overapproximate(cap::Intersection{N, <:LazySet, S},
                          dir::AbstractDirections{N};
-                         upper_bound::Bool=false,
                          kwargs...
                         ) where {N<:Real, S<:AbstractPolytope{N}}
 
@@ -263,12 +241,11 @@ function overapproximate(cap::Intersection{N, <:LazySet, S},
     Hi = constraints_list(P)
     m = length(Hi)
     Q = HPolytope{N}()
-    ρ_rec = upper_bound ? ρ_upper_bound : ρ
 
     for di in dir
-        ρ_X_Hi_min = ρ_rec(di, X ∩ Hi[1], kwargs...)
+        ρ_X_Hi_min = ρ(di, X ∩ Hi[1], kwargs...)
         for i in 2:m
-            ρ_X_Hi = ρ_rec(di, X ∩ Hi[i], kwargs...)
+            ρ_X_Hi = ρ(di, X ∩ Hi[i], kwargs...)
             if ρ_X_Hi < ρ_X_Hi_min
                 ρ_X_Hi_min = ρ_X_Hi
             end