The advantage of our enumeration algorithm is also highlighted in situations where it is difficult to determine which mapping is chemically correct even using expert chemical knowledge. This advantage is demonstrated in reaction 22 from the dataset, as shown in Figure . Reaction 22 is the synthesis of oxazolidinone using the amino acid proline and ethyl chloral hydrate as substrates. Our proposed algorithm found two possible candidate mappings for this reaction with applying the aforementioned fil- ter2. The difference between these mappings lies in the origin of the inner-ring oxygen of oxazolidinone: in the left case, it originates from the hemiacetal; in the right case, from the carboxylic acid. The original paper of the benchmark dataset considered the left, esterificationlike mechanism to be correct. However, several studies have reported that this type of reaction can proceed through a nucleophilic attack by the oxygen of the carboxylate in proline on the C=C bond of an enamine produced from the aldehyde (originating from the hemiacetal) and proline. Therefore, the right mechanism is also a chemically plausible alternative in this context, and further investigation may be required to determine which candidate mapping is actually correct. In this way, our algorithm generates possible candidate mappings, allowing chemists to determine the correct mapping by consulting the literature or conducting ex-periments, if necessary.