Merge pull request #1894 from SciML/myb/irred

If the RHS of an alias doesn't appear in the equations, then it's reducible

Author: YingboMa

src/structural_transformation/partial_state_selection.jl

@@ -289,10 +289,9 @@ function dummy_derivative_graph!(structure::SystemStructure, var_eq_matching, ja
             isred
         end
         for (k, (c, v)) in ag
-            isreducible(k) || push!(irreducible_set, k)
             isreducible(k) || push!(irreducible_set, k)
             iszero(c) && continue
-            push!(irreducible_set, v)
+            isempty(𝑑neighbors(graph, v)) || push!(irreducible_set, v)
         end
     end
 

src/systems/systemstructure.jl

@@ -206,7 +206,6 @@ function TearingState(sys; quick_cancel = false, check = true)
     ivs = independent_variables(sys)
     eqs = copy(equations(sys))
     neqs = length(eqs)
-    algeqs = trues(neqs)
     dervaridxs = OrderedSet{Int}()
     var2idx = Dict{Any, Int}()
     symbolic_incidence = []
@@ -259,7 +258,6 @@ function TearingState(sys; quick_cancel = false, check = true)
         push!(symbolic_incidence, copy(statevars))
         empty!(statevars)
         empty!(vars)
-        algeqs[i] = isalgeq
         if isalgeq
             eqs[i] = eq
         else