Fix nghyd#226 (for real)

src/pab/cloisons.ts

 import { CalculatorType } from "../compute-node";
-import { Nub } from "../index";
+import { Nub, Pab, StructureParams } from "../index";
 import { ParamCalculability } from "../param/param-definition";
 import { ParallelStructure } from "../structure/parallel_structure";
 import { StructureKiviParams } from "../structure/structure_kivi";
@@ -26,6 +26,13 @@ export class Cloisons extends ParallelStructure {
         return loiAdmissiblesCloisons;
     }
 
+    /**
+     * Is the Nub used in a PAB?
+     */
+    get isInPAB(): boolean {
+        return (this.parent !== undefined && this.parent instanceof Pab);
+    }
+
     public Equation(sVarCalc: string): Result {
         this.updatePrms();
         return super.Equation(sVarCalc);

src/structure/parallel_structure.ts

@@ -30,6 +30,9 @@ export class ParallelStructure extends Nub {
 
     public set structures(structures: Structure[]) {
         this._children = structures;
+        this._children.forEach((s) => {
+            s.parent = this;
+        });
     }
 
     /**