Re: [Swarm-Modelling] Announce: metaABM 1.0.0

[Marcus G. Daniels]

Hi Miles,

Consider a model of disaster response.    Let's say a city planner wants 
to estimate how much money to put into local emergency response, so they 
hire an agent modeler to model their city under crisis scenarios.  After 
a modeling framework has been implemented and has been given some 
exercise by the modeler. the planner would like to run it from their PC 
to refine their ideas.
The modeler is fluent in various programming languages, but the planner 
has no programming experience.

Suppose a population of people in the vicinity, having different 
socioeconomic status, social dependencies, skill sets, work obligations, 
and so on.   Whether or not a person gets involved in helping, and how 
they help is determined by factors like these.   Engagement might depend 
on the perception of how much help is already at work, variations in 
feelings of social connectedness to the community, and prevalent notions 
of group identity.   Or it might also depend on the influential city 
politicians or wealthy individuals.

In the model, individuals go about their business, and devote some 
attention to various matters, including this perturbation event.
The model runs for a couple months, and `bad' consequences occur or not 
after the disaster.    Then the modeler or planner goes back and tweaks 
the model to identify possible short term and long term investments that 
may help mitigate risk for the city overall and/or sufficiently 
influential stakeholders.

One thing the planner wants to consider is creating incentives for 
people to help in the community with the idea that will increase the 
probability of engagement during a crisis -- whether that's through 
ongoing charitable donations or through meals-on-wheels or whatever.    
Therefore it becomes important to study the demographics of the city in 
detail and find ways to match incentives to the lifestyles that exist 
through the city.   In the end the problem is a large constraint 
satisfaction problem, where each individual decides to direct their 
energy in certain individual-specific ways from a larger set of options 
depending on estimates of and experience with payoff.    The idea is to 
calibrate and validate a model over time by attempting low-cost and 
low-risk interventions (e.g. propaganda might be an intervention) and 
measuring how it works.  When some success is gained, then move on to 
higher-cost and higher-risk interventions.

Here the division between customization and inheritance is not clear.  
The important parts of the model are rules that concern psychology and 
concern political leverage.   It seems to me that such rules would 
always be in flux and not convenient for rigid declarative abstraction, 
nor will they be convenient to punt to an external class.    The user 
will need to think in detail about the propositions they are making 
about city inhabitants and they will need to have flexibility in 
expressing those ideas.  The kind of runtime that can do this ought to 
have a convenient and direct (not indirect or preconceived) 
representation for the individuals and the things those individuals can 
learn to do.

I don't doubt many familiar ABMs are compatible with simple domain 
specific languages.  But in the end, I think the challenge is not to 
avoid programming at all cost (a.k.a. thinking and speaking carefully), 
it's to hide irrelevant complexity.  One way is to make, use and adapt 
macros.¹  To the extent I'm skeptical with metaABM, it's because I don't 
see how the user is directly empowered to critique and specialize the 
macros (the developer's view of things) without dropping into Java.

As for the matter of how to get others in the academic community to 
accept agent-based models, I'll just say I'm not very sympathetic.   
Software must people read each others' code all the time.   Yeah, it's 
hard.  Try harder.   If we use functional programming to make models 
(say iterate XSLT on XML model specifications!), making a serious effort 
to factor the code, and then (most importantly!) gratuitously rename all 
variables to be single greek characters, then after a while hopefully 
someone will notice ABMs are pretty much just math anyway!

Marcus

¹ I don't mean "macros" is any denigrating sense like a C #define or an 
editor shortcut -- I mean it in the sense of fully-general code 
generation up to and including runtime native code compilation -- as is 
possible with modern Common Lisp implementations.