How to write correctly: "not who" or "someone"?
You need to consider the whole proposal. Compare:
"Someone took one apple from you ... How many apples do you have left?" In this case, the word "Someone" means "someone" and must be written together.
"Dinner was not prepared by anyone, but me!" In this case, "not" is a particle, and is written separately.
To understand how a given word is spelled correctly, you first need to parse its meaning.
one (with emphasis on the first vowel) is
Accordingly, the word "someone" is spelled togetherAs is an indefinite pronoun, which can be used only in the nominative case (the word answers the question: who? what?)
EXAMPLE: Someone Chertinsky O.A. robbed the apartment of the Sidorov couple.
The word "someone" also has synonyms: these are the words "someone" and "some", which can be easily replaced by "someone" itself and the meaning of the sentence will not be lost. This is clearly seen in the above example.
EXAMPLE: Someone robbed the apartment of the Sidorov couple.
EXAMPLE: A certain Chertinsky O.A. robbed the apartment of the Sidorov couple.
You should write together, "one", and pronounced with an emphasis on the first syllable. Someone is a certain unknown person or who wished to remain so. Or it is a named, but little-known person, about whom they say in the spirit:" Someone Petrov asked you to convey ... "
In the word "someone", "not" is a prefix, "-to" is a root.