Union With the Empty Set - March Madness!!!! Day 23 - Prompt: Union

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Union With the Empty Set

was the topic in today's AP math class. A safe topic, right? Not when Jenny was on my mind. I kept thinking about a post on that Iowa Cold Cases site. Something about a man who used algorithms to determine that a serial killer was at work, but the local police blew him off--until the mounting body count convinced them to look at his humble little math equation.

There are an estimated 2,000 serial killers living at large in the U.S. Now, an algorithm can help find them, writes @elbuder

Thomas Hargrove utilized his software to discover and alert the police department in Gary, Indiana of 15 unsolved strangulations in the area. “It was absolute radio silence,” he says in the film. “They would not talk about the possibility that there was a serial killer active.” After Hargrove was rebuffed, seven more women were killed. He says it was “the most frustrating experience of my professional life.”

Rebuffed by the police and case investigators. That theme ran rampant through all the cold cases. Hargrove used math to obtain data himself. Math is God, I've always said, and this guy was proving it in ways I wouldn't have thought of myself.

Linkage Blindness

sounded like something that afflicted our own local LE. Along with denial, selective amnesia, and scapegoating. Blame the Victim. Waste no time or taxpayer dollars investigating the murder or disappearance of anyone who had any kind of connection with drugs or felonies.

Jenny's felony, attending a party and having a plastic bag of weed in her pocket, was so trumped up we couldn't believe she actually served time in jail for it. There went a college scholarship. There went a future. Working at Hooters was fun at first, she wrote in her diary, but it didn't take long for her to get sick of the drunks hittng on her.

"Kristy," Mr. Kowalski said. I focused on the overhead projector. Dang.

"Could you repeat the question please?"

He smirked. "I hadn't asked it yet."

Thank God there were no mean girls in AP Algebra.

"What happens when we take the union of any set with the empty set?" Mr. K asked me.

"Funny you should ask." I decided to go out on a limb here, maybe due to latent anger over the Emily D poem in AP Lit class. I'd been poring over Jenny's journal, the one concealed in a high school Algebra notebook. Rosary Man was like one element in a set of people who had face to face interactions with Jenny in recent weeks. Who else was in the set?

Mr. K folded his arms, waiting for me to say more.

"This is grade-school math question," I dared to say. "The empty set is the set with no elements. Joining it to another set will have no effect. The union of any set with the empty set will give us the original set back."

"And what's funny about this?"

"I've been looking at algorithms, set theory, and even string theory," I said, "in hopes of figuring out where my sister might be. She's the empty set right now. I've been looking at sets of people who knew her and I've tried combining them, but I never get Jenny, the original set, back."

His Adam's apple bobbed. He cleared his throat. Everyone was staring at me, then at him.

"You should read up on the Algorithm man," I said, "and show the video in class. As a reporter he was known as the math guy. He created a data base of unsolved murders, then used an algorithm to solve an informatics problem."

The silence unsettled me. I wasn't used to holding the floor like this.

"I would suggest you write a paper about this for extra credit," Mr. K said. "Not that you need it."

He scribbled more equations on the overhead projector. I thought about writing a paper, using it in AP Lit Class, and maybe sending it to the Gazette and the Des Moines Regiter and every other newspaper in the state.

“Linkage blindness” was a problem in cold cases, this guy Hargrove said. In the U.S. justice system, “the only way a murder is linked to a common offender is if the two investigators get together by the water cooler and talk about their cases and discover commonalities.” His algorithm can identify clusters of unsolved murders which are related by the method, location, and time of the murder, as well as the victim’s gender.

Not that I considered "Jenny's death" to be in the realm of possibility. I had avoided Alicia Angel ever since the "Status Update: Dead" incident. Whatever I said to Mr. Cook that day must have scored some kind of cred, because he got Alicia to apologize to me, a lame token gesture if ever there was one, and me to apologize for punching her, though my only regret was that I'd been called over the carpet for it.

At lunch, my mind was still caught up in mathematical certainties and probability versus possibility. Probability is the branch of mathematics that deals with uncertain events. Jenny's location, status, and future were not just uncertain; they were total unknowns. Jenny's disappearance was not a random event. There were methods for solving this equation, if I could just figure them out. I picked the brains of Ty Christy and Breanna, but they were still going on about portals and alternate dimensions. What a letdown. The brightest minds in the school all caught up in the juju of New Age physics.

Sara Lacy, our resident security officer, seemed a more sensible person to hit up for ideas. I caught her on my way out of the lunch room. Of course she had heard of Hargrove and Linkage Blindness. She loved telling students that solving crime is never like TV because it involves long hours of trying to get people to talk, taking down witness statements, searching computers and court house records, and sitting in a car for hours waiting for some perp to leave the house. Car chases and pursuits on foot were rare, and she was glad.

"I need help," I told her. "My parents won't tell me what the police are saying. Who they're interviewing. I only recently found out about the Uber driver because Jenny prepaid him for a ride home that never happened. It was in her credit card statement. I copied off a few pages of her journal, but nobody's telling me anything about a guy who gave her some kind of heirloom rosary beads. I want to talk to patrons at Hooters myself but Mom and Dad won't hear of it."

Sara nodded. "Can't say that I blame them. But you could show me whatcha got, and I might go undercover and ask around on your behalf."

Gotta love Sara Lacy!

I couldn't wait to get home, get through chores and dinner, then tackle the pages of Jenny's journals once more. The clues were there, like numbers and symbols in a mathematical equation.

Jenny, you're not an empty set. You are alive somewhere. Hear me. Kristy here, the warrior sister. Stay strong, Jenny. So help me God, or so help me physics, I will find you!

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