Sentence 1: It shouldn't be any longer than four feet or it will be too heavy.

Sentence 2: If it's bigger than four feet then it will be too heavy to carry.
Is this second sentence entailed by the first?

Answer: yes

Sentence 1: Yes, Kentucky. He answered the first words his father had ever addressed to him.

Sentence 2: He doesn't have a father.
Is this second sentence entailed by the first?

Answer: no

Sentence 1: I will speak with your visitors as I agreed, if they come.

Sentence 2: If your visitors come, I will talk to them.
Is this second sentence entailed by the first?

Answer:
yes