I read the article below.
Henry had no brothers and no sisters. "I want a brother," he told this parents. "Sorry," they said.
Henry had no friends on his street. "I want to live on a different street," he told his parents. "Sorry," they said.
Henry had no pets at home. "I want to have a dog," he told his parents. "Sorry," they almost said. But first they look at their house with no brothers and sisters. Then they looked at their street with no children. Then they looked at Henry's face. Then they looked at each other. "Okay," they said.
Is "no brothers and no sisters" equivalent to "no brothers and sisters"?
Best Answer
It is common to see no brothers or sisters as a way to say that someone is an only child. The way it is said in your quote, no brothers and no sisters, is less common but it emphasizes the fact that there are no other children. These two phrases, no brothers or sisters and no brothers and no sisters are equivalent. However, no brothers and sisters is not equivalent.
If you are familiar with first-order logic from mathematics, or Boolean algebra from a computer class, this is an example in English grammar of De Morgan's laws. De Morgan's laws are basically a set of rules specifying how a negation distributes to multiple objects.
If p represents brothers and q represents sisters, then in logic the phrase no brothers and no sisters would be
~p AND ~q. In logic, this is equivalent by one of De Morgan's laws to~(p OR q), which we say in English as no brothers or sisters.Please note that English grammar and syntax does not always follow the rules of logic, I only used it as a way to illustrate the grammar rule for this simple case.