In this paper we propose an efficient and incremental plan recognition method for cognitive assistance. We design our unique method based on graph matching and heuristic chaining rules in order to deal with interleaved and sequential activities. The finding of this research work is to be applied to predict abnormal behavior of the users, and optimize assistance for them. We have studied a use case of kitchen environment during lunch time that we will discuss in this paper and targeted Dementia patients. We will present implementation details as well as our evaluation plan.