Continuing the mishnah... With regard to joint ownership. What if only one is prohibited from the benefit of that which jointly owned? It's the same rationale for prohibition or permission. Likewise, what about property or tools that are leased to the public (eg - a bathhouse or an olive press) - it will depend on whether the owner who has sworn off another getting benefit depends on whether the owner actually has any rights to the leased property/tools. Also, what happens when one says another can't get benefit, imposed on another, as compared to one taking a vow upon oneself. The Gemara here is looking at the subtleties of the vow, of course. Plus, the Gemara on that bathhouse or olive press - which is leased - when the holding is partial to begin with