The phrase "a necessary term" is correct and usable in written English.
You can use it when referring to a word or phrase that is essential or required in a particular context or discussion.
Example: "In legal documents, clarity is crucial, and using a necessary term can prevent misunderstandings."
Alternatives: "an essential term" or "a vital term".
Speaking now in more technical terms, a necessary condition for X to be a complete intersection is that the sheaf of ideals ({mathcal {I}}_X) be arithmetically Cohen-Macaulay (ACM, for short), which means that all higher cohomology groups (H^i({mathbb {P}}^N, {mathcal {I}}_X(d)) = 0) vanish for (n ge i >0) and (forall d in {mathbb {Z}}).
Maximizing employment and output is a necessary condition for long-term growth, which can only be done with aggressive fiscal policy.
To develop our model, let us suppose that maintenance of lung epithelium involves the steady turnover of a single, multipotent, functionally equivalent (i.e., equipotent), tissue-maintaining population, a necessary condition of long-term tissue homeostasis.
Thus, through preventing the action of Muller's ratchet, HGT could be a necessary condition for the long-term survival of prokaryotic populations.
The White House, under the guise of providing a necessary short-term stimulus to the economy the short term being a period that ends on Election Day—has stored up a lot of trouble for the future.
Air strikes represent a necessary short-term reaction to an immediate threat, but they are not a long-term solution.
It is a necessary, short-term, intermediate pain to pay for the absolute minimum hope of survival, which is a gracefully declining population, because if you don't do that you will have a rapidly imploding population one day.
During the transition, a few of us might end up being "superrich," rather than wealth being redistributed widely, but this is a necessary short-term cost.
Having introduced the necessary terms, we now turn to our main topic.
