I think my most interesting achievement for this month has been getting the "detective story" wrapped up. This is something I've been gradually working on in the background for the last few months. I back-burnered story understanding to focus on advancing game-playing and rule learning this year, but I wanted to do a little something with it. Even the simplest murder mystery, as it turned out, introduced some new wrinkles that called for Narrative Engine upgrades.
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| Frederic Dorr Steele's illustration for the Sherlock Holmes story "The Adventure of the Dying Detective" as published in The Strand Magazine. |
First there's the protagonist's motivation. While they might have personal reasons for solving a particular crime, in many cases they're a professional doing a job. Jobs are in essence packages of sub-goals, all nested under the parent goal of "perform job." I discussed this precursor for the detective story back in the July diary.
I also needed a way to express the essential mystery: who committed the murder? And why does the protagonist need to know, anyway? I was able to handle this through a small extension of my existing system of action prerequisites. In previous stories, I've been able to indicate a character's motivation for being in a particular place because they can't do anything with an object unless they are in the same place with it. And they can't go to where an item is unless they know where it is. Similarly, it is not possible for an agent to do anything with an entity unless they know which entity they want to target. If an agent has a goal tied to someone/something that is identified by a characteristic (such as "the human who committed a murder"), the goal cannot be fulfilled without identifying which of the available entities has that characteristic. This provides a general motivation for the need to know "who" or "which one" that is not unique to murder mysteries.
Here's the final detective story:
"Jack was a detective."
"Jack wanted to work Jack's detective job." <Acuitas should really *assume* this if not told otherwise, but doesn't yet>
"Howard was a man."
"Vincent was a criminal."
"Vincent hated Howard."
"Vincent murdered Howard."
"Frank was a man."
"Frank was where Howard was murdered."
"Sally was a woman."
"Sally wanted Howard's money."
"If Sally murdered Howard, Sally would get Howard's money."
"Jack wanted to arrest who murdered Howard."
"But Jack did not know who murdered Howard."
"Jack asked a witness who murdered Howard."
"The witness told Jack that Vincent murdered Howard."
"Jack arrested Vincent."
"The end."
The various possible motives for the murder are immaterial, at this point. Acuitas can make predictions of what someone might do from what they want to do, but can't yet reason backward from a deed to who probably did it. So his understanding of Jack's success rests on being explicitly told that Vincent did the murder. Given that, he is capable of inferring 1) a crime has been done, 2) Jack solved a crime by arresting the person who did it, and 3) Jack did his job.
The final quirk of this story is that you could say it has a good ending even though there is a casualty - Howard is dead at the end. Up until now, Acuitas has assessed stories by checking whether everyone has solved all of their problems. If Howard's death got registered as a problem, he would consider this story to have a sad ending no matter how everything else turned out. So I adjusted the assessment method to look at whether things have meaningfully improved between the story's lowest point and its conclusion. In the future, I want Acuitas to try to determine what the story's main thread is - what it is about - and focus on whether that resolves well. Supposing this story were about an attempt to resurrect Howard, his remaining dead at the conclusion might still amount to a sad ending. But it isn't about that.
Until the next cycle,
Jenny
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