Follow project on Twitter

Problem description 2: Possessive reasoning

Besides past tense reasoning, also possessive reasoning – reasoning using possessive verb “has/have” – is not supported by predicate logic (algebra). So, “Three apples plus four apples are seven apples together” can be expressed in algebra, because it contains “is/are” in the present tense. However, “John has three apples and Paul has four apples. Together they have seven apples” can’t be expressed in algebra.

Now a reasoning example instead of a calculation:
> Given: “Paul is a son of John.

• Logical conclusion:
< “John has a son, called Paul.

Or the other way around:
> Given: “John has a son, called Paul.

• Logical conclusion:
< “Paul is a son of John.

So, why doesn't predicate logic (algebra) support past tense reasoning in a natural way? Why should any predicate beyond verb “is/are” in the present tense be described in an artificial way, like has_son(john,paul)? Why is algebra still not equipped for natural language, after those centuries of scientific research?