What are the rules, limitations, etc. of using a trademarked product, by name, in a work of fiction?
To be specific, I had an idea for a short story last night where a phone AI (a bit more advanced than the current ones, but not implausibly so-- It’d be set in the future) is one of the two “characters”. It’d be simplest for me to just introduce the AI as “Siri”, which would quickly and easily let the readers know what they’re dealing with, but on the other hand, I can see how that might get Apple’s lawyers upset. Of course, I could just play it safe and give the AI some other name, and either explicitly explain what it is, or just trust my readers to figure it out.