  The construction of large open knowledge bases (OKBs) is integral to many
applications in the field of mobile computing. Noun phrases and relational
phrases in OKBs often suffer from redundancy and ambiguity, which calls for the
investigation on OKB canonicalization. However, in order to meet the
requirements of some privacy protection regulations and to ensure the
timeliness of the data, the canonicalized OKB often needs to remove some
sensitive information or outdated data. The machine unlearning in OKB
canonicalization is an excellent solution to the above problem. Current
solutions address OKB canonicalization by devising advanced clustering
algorithms and using knowledge graph embedding (KGE) to further facilitate the
canonicalization process. Effective schemes are urgently needed to fully
synergise machine unlearning with clustering and KGE learning. To this end, we
put forward a multi-task unlearning framework, namely MulCanon, to tackle
machine unlearning problem in OKB canonicalization. Specifically, the noise
characteristics in the diffusion model are utilized to achieve the effect of
machine unlearning for data in OKB. MulCanon unifies the learning objectives of
diffusion model, KGE and clustering algorithms, and adopts a two-step
multi-task learning paradigm for training. A thorough experimental study on
popular OKB canonicalization datasets validates that MulCanon achieves advanced
machine unlearning effects.
