A concurrent estate in which each tenant owns an undivided interest in the whole estate with survivorship rights.

The right of survivorship: Upon the death of one of the joint tenants,the decedent's share passes automatically to the surviving joint tenant.

O grants Blackacre "to A & B as joint tenants."

A dies, leaving a will with C as sole heir.

Who owns Blackacre?

B owns all of Blackacre by right of survivorship. C gets nothing.

Can you explain why C gets nothing here?

The second scheme is that.

O grants Blackacre "to A & B as joint tenants."

A sells her interest to C without telling B, thus severing the joint tenancy.

A dies. B asserts complete title to Blackacre under his assumed right of survivorship in a joint tenancy.

Who owns Blackacre?

B and C are now tenants in common with no right of survivorship in B, which was destroyed by A's severance to C.

Can you explain why in the first scheme, C gets nothing, but the second one, C will get the property?

consider the following the situation

O grants Blackacre "to A & B as joint tenants."

A dies, leaving a will with all his interest in Blackacre to C.

For this situation, could I consider the will as a seller of a property, which makes B and C tenants in common with no right of survivorship in B, which was destroyed by A's severance to C?