Bayesian Updating: A Cyber Pastoral

Dylan Randall Wong

white fence surrounds the plastic farm animals 
and the white farmer two shades whiter 
than the blank paper on my chromebook screen 
the illusory sheen white fence 
a rustic symbol an open dream 
the white fence is no barrier at all for me 
ascended with a single vault 
and then green screen everywhere 
fuzz of greens and browns 
I lie in it trying to forget the white fence that obscured the data 
because I have to run the gamut just to stay on top of my projections 
with maximum a posteriori the code compels me to climb the posterior 
and then at the peak

haze dots the peaks of the graph on my chromebook screen 
I squint through the data forests’ shadow 
there a hint of a pattern 
I reconfigure my garden of forking paths anew 
shake off the fuzziness 
but there in the woods’ shadow 
the prongs of a threat appears 
so with a precise stroke I eliminate that interval of data 
possibly a wood shadow ghost monster
perhaps befriended by my Bayesian golems 
I remind them not to make the wrong kind of friends 
after dry sterile thunder then downpour 
we stay warm mossy overhang 
and we cave paint with crushed bryophytes and excess rain we get

paste like herbal butter and mud 
the brown a touch too green 
the sludge I swipe off my screen 
its texture surprisingly solid grip 
like the endurance of moss on rock 
where there is no water 
and the sludge comes to obscure 
what the thunder said 
and so I could not hear from where arose 
the strength that walked beside you 
which held your roots to the rock 
oh bryophyta you endured again and again 
across the updating and in time 
retained the water for the shadow to drink again

yet impossibly the path dependency is getting to me 
and the accretion of layers sloughs and amasses like a latent desire 
and only in this desire is a poem found 
so I revert to my prior
where there is both rock and water and rustic symbol of streams 
and the frogs croak contentedly 
belly buttered pattering proximate mud colored picture perfect 
and my cave paintings somehow endure throughout 
for nothing less than belief endures but

through the screen window the forest sways unsteadily 
winds blowing every which way like an illusion 
and my friendly golems 
peeking out from behind the sorted green columns 
beckon to me 
so with a resigned sigh I return to the garden of forking paths 
where I assume Borges’ good Chinese Doctor Tsun 
and explore the data like his grandfather before him 
stranger in a strange land 
seeking integration over those final intervals

blink at the closing window of an open dream 
for there the old farmer squints at me 
rough hands clench his pitchfork 
probes with defensive words and vigilant eyes fluorescent 
and my stomach churns at this dose of raw data 
the green screen folds in on itself 
leaving me fuzzy and clinging to the dry rocks 
am I valid I finally whisper to myself 
and the Chinese boy beside me whispers back 
you are bryophyta of the rocks 
and you will likely endure somewhere else if differently

back out among green columns in the forest of forking data 
as I had frequented so many cycles ago 
where old trees once stood tall against winds of evidence 
not surrounded by white fences 
though I remember them now only as sunlight on a broken column 
and I return to the overhang 
where my golems and I painted with brown and green paste 
just as I remember it the paintings still endure 
with a finger’s stroke I brush away the blurriness of uncertainty and forgetting 
to reveal all that is left behind 
all the priors and parameters and adjustments 
in all their subjectivity and imprecision 
nothing is ever certain

so it is only perhaps that I am there under the rock, back leaning against green columns
renewed as my golems lounge around beside me, typing up a poem on my chromebook
in the morning sun.

The Science

Bayesian methods are becoming increasingly prevalent in the social sciences. Bayesian updating denotes the mathematically precise procedure of updating one's state of belief (from prior to posterior) given new evidence. The posterior replaces the old prior and becomes a new prior. I weave this idea through my poem as the speaker works his way through the labyrinthine world gathering new data - or perhaps through a world of data.

The archaeological element can be found where the speaker rediscovers his prior state of belief on the cave walls - retracing how he arrived where he did, looking for where to begin again. The recurring image of golems is borrowed from Richard McElreath's excellent introduction to Bayesian statistics, which was my first introduction to the topic.

The Poet

Dylan Randall Wong is an aspiring clinical psychology researcher who recently graduated from Reed College – he currently lives in Portland, Oregon, but Singapore is his home. His artistic goal is to deepen the convergence of science and creative writing. His poetry and short story fiction have been published in the SG Poems 15-16, anima methodi and Atelier of Healing poetry anthologies, and the this is how you walk on the moon short story anthology, respectively.

Next poem: Cemetery at Lindisfarne (Trench 2) by Jodie Hannis