That the allocation $x$ is a strong core allocation is
If it is a strong core allocation, it is efficient and individual rationality.
Individual Rationality:$x_i \succsim_i w_i \quad \forall i \in I$
This page is auto-translated from /nishio/強コア配分 using DeepL. If you looks something interesting but the auto-translated English is not good enough to understand it, feel free to let me know at @nishio_en. I'm very happy to spread my thought to non-Japanese readers.