Tag Archives: Markov chains

Stylin’ Science Part: Bla Bla Bla – Markov Stochastic Processes via Swiper the Fox


So I sometimes babysat my niece during her Dora the Explorer phase.  Until then, I truly believed that there could not possibly be a childhood character more annoying than Barney.  I was wrong.  Those three words would remain in my head long after my brother or sister-in-law would come to pick my niece up.  Those.  Three.  Words.   “Swiper, no swiping.”  “Swiper, no swiping.”  “Swiper, no swiping.” “No, really, I can’t … I just can’t anymore.  Please stop swiping, Swiper.  Or else, things might get ugly.  Very ugly.  Very quickly.”  And that’s why I’m having my most favoritest fox in the world help me explain Markov stochastic processes.  Now, this particular stochastic processes is named after Andrey Markov, a deep, dark, sexy Russian mathematician, as opposed to the deep, dark, sexy Russian former spy, Anton Zelov, in Order of The Dimensions, who … oh, that’s right.  You don’t care.

So anyway, a Markov process is one where the probability of the most current event happening depends on the most recent event, but not on any events prior to the most recent event.  Now, there’s a lot of stuff that can happen depending on the last event.   But let’s start with a simple example.  So let’s say Dora has a Harry Potter wand, Hunger Games DVD, Twilight nail polish set, and a copy of this mess in her backpack.  If Swiper took the wand last time, he might try to take it again with a probability of 30%  or he might take the DVD with  a probability of 40% or he might take the nail polish set with 30% probability.  So unless Dora says,    “Swiper, no swiping. Swiper, no swiping. Swiper, no swiping.”, he is most likely to take the DVD next.  Notice that this mess has a 0% probability of being swiped.  But if Swiper took the DVD last time, let’s say, Swiper will take the wand with 20% probability, the DVD with 30% probability, and the nail polish set with 50% probability.  So unless Dora says,   “Swiper, no swiping. Swiper, no swiping. Swiper, no swiping.”, he is most likely to take the nail polish set.  Again, notice that this mess has a 0% probability of being swiped.  Now, let’s make things a little more interesting and introduce something called the absorbing state, meaning once a particular event happens, only one type of event can happen after that.  So, for example, if Swiper took the nail polish set last time, Dora will take out this mess out of her backpack and say, “Swiper, please swipe. Swiper, please swipe.  Swiper, please swipe.” with 100% probability to which Swiper will reply, “Aw, man!” before reluctantly taking it.  Now, I don’t know about you, but I for one would not at all feel sorry for the shifty, unscrupulous son of a vulpes vulpes, after how he almost swiped my last ounce of sanity during those evenings I spent watching episode after episode … after episode of my niece’s beloved television program at the time.  But anywhoo … until next time … Swiper, no swiping.  Unless it’s this mess – please feel free to swipe it at any time.