+ auto V1Elems = ShadowElements.find(V1);
+ auto V2Elems = ShadowElements.find(V2);
+ if (V1Elems != ShadowElements.end() && V2Elems != ShadowElements.end()) {
+ if (std::includes(V1Elems->second.begin(), V1Elems->second.end(),
+ V2Elems->second.begin(), V2Elems->second.end())) {
+ return V1;
+ } else if (std::includes(V2Elems->second.begin(), V2Elems->second.end(),
+ V1Elems->second.begin(), V1Elems->second.end())) {
+ return V2;
+ }
+ } else if (V1Elems != ShadowElements.end()) {
+ if (V1Elems->second.count(V2))
+ return V1;
+ } else if (V2Elems != ShadowElements.end()) {
+ if (V2Elems->second.count(V1))
+ return V2;
+ }
+