| Uri src, Uri tgt -> UriManager.eq src tgt
| Sort (Cic.Type _), Sort (Cic.Type _) -> true
| Sort src, Sort tgt when src = tgt -> true
| Uri src, Uri tgt -> UriManager.eq src tgt
| Sort (Cic.Type _), Sort (Cic.Type _) -> true
| Sort src, Sort tgt when src = tgt -> true