I want to express my knowledge about the presence of absence of something. My knowledge is divided into three different cases:
- I know that the thing doesn't exist.
- I don't know whether the thing exists.
- I know that the thing exists.
Sadly, neither of those is the negation of another one. However, I can define four cases, where each case is the negation of another case:
- Something is allowed to exist. (allowed)
- Something is allowed to be missing. (???)
- Something is guaranteed to exist. (guaranteed)
- Something is guaranteed to be missing. (prohibited)
I want to describe each of these cases by a single word, which is supposed to clearly distinguish it from the other three cases. As you can see, I already found three of the words. However, in the second case I am unable to find one.
Let me expand on what I mean by the negation. Consider the following table:
|phrase||single word||doesn't exist||don't know||exists|
|allowed to exist||allowed||no||yes||yes|
|allowed to be missing||???||yes||yes||no|
|guaranteed to exist||guaranteed||no||no||yes|
|guaranteed to be missing||prohibited||yes||no||no|
Note, that the first and the fourth case are supposed to be negations of each other, just like the second and the third case. Thus, if I say that something is not allowed to exist (allowed), then it is guaranteed to be missing (prohibited). Also, if I say that something is not allowed to be missing (???), then it is guaranteed to exist (guaranteed).
Thus, my question is: Which single word is able to replace the phrase "allowed to be missing"?
This question can be rephrased to: Which single word is the exact negation of "guaranteed to exist"?
The context is theoretical computer science. Here are two example sentences, which are negations of each other:
- The connection from x to y is allowed and the connection from y to z is guaranteed.
- The connection from x to y is prohibited or the connection from y to z is allowed to be missing.
I think the most helpful wording is the one suggested in this answer, using terms from modal logic:
- The connection from x to y is possible and the connection from y to z is necessary.
- The connection from x to y is not possible or the connection from y to z is not necessary.
Thanks for all the answers =)