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in Chat

I just read all the other introductions. What an interesting and varied crowd! This should be fun!

I came here from the https://www.valueflo.ws/ project where we are working on a set of common vocabularies and protocols for economic networks. I think they are compatible with category theory, and want to find out if and how deeply that is true in this course. If so, we should be able to put a better mathematical foundation on our efforts.

We have also been invited to work on a project this summer called "Accounting for planetary survival" where we will really need a better mathematical foundation.

The lemon meringue pie process flow in the preface to the book reminds me of something we did in one of the valueflows-related software experiments valled NRP (Network Requirements Planning): https://speakerdeck.com/mikorizal/salsa-recipe-plan-reality

Gives me more confidence that this will be relevant.

## Comments

We'll do the salsa and the merengue!

I wish I had time to read about "a set of common vocabularies and protocols for economic networks". I'm really interested. But not today - too busy approving applications and trying to get LaTeX to work on this forum!

Who is the "we" who has been invited to work on "Accounting for planetary survival"? And who invited you? Sounds important.

`We'll do the salsa and the merengue! I wish I had time to read about "a set of common vocabularies and protocols for economic networks". I'm really interested. But not today - too busy approving applications and trying to get LaTeX to work on this forum! Who is the "we" who has been invited to work on "Accounting for planetary survival"? And who invited you? Sounds important.`

"We" is me and Lynn Foster, who is one of the core group on the Value Flows project. We were invited by Michel Bauwens of the P2P Foundation. https://p2pfoundation.net/

They haven't published anything about that project yet, but here is some related info: http://wiki.p2pfoundation.net/Category:P2P_Accounting

`"We" is me and Lynn Foster, who is one of the core group on the Value Flows project. We were invited by Michel Bauwens of the P2P Foundation. https://p2pfoundation.net/ They haven't published anything about that project yet, but here is some related info: http://wiki.p2pfoundation.net/Category:P2P_Accounting`

Bob,

It's great to see you here. I looked briefly at value flow networks (I saw it mentioned in a Michel Bauwen's blog post). I thought this was a natural fit for the categorical informatics that will be the subject of Chapter 2 of this course. I'll be curious to get your thoughts.

`Bob, It's great to see you here. I looked briefly at value flow networks (I saw it mentioned in a Michel Bauwen's blog post). I thought this was a natural fit for the categorical informatics that will be the subject of Chapter 2 of this course. I'll be curious to get your thoughts.`

@Brad Venner, thanks for your interest. I'll ping you when I get to Chapter 2.

`@Brad Venner, thanks for your interest. I'll ping you when I get to Chapter 2.`

Likable applied area here also! After some superficial reading on Leontief input-output models I was left under the impression that some further categorical treatment could be applied to them. I have in my reading queue a work in Spanish called "Reformulacion del modelo de Leontief a traves de redes de Petri", Molina & Gutierrez (reformulating Leontief model through Petri Nets), where in turn Petri Nets are understandable in terms of monoidal categories. This kind of modeling I gather that is used at country-wide scales by policymakers and is an element of several national accounting systems, and real data is gathered by statistic means to characterize the particular economies. There is a dynamic version also.

`Likable applied area here also! After some superficial reading on Leontief input-output models I was left under the impression that some further categorical treatment could be applied to them. I have in my reading queue a work in Spanish called "Reformulacion del modelo de Leontief a traves de redes de Petri", Molina & Gutierrez (reformulating Leontief model through Petri Nets), where in turn Petri Nets are understandable in terms of monoidal categories. This kind of modeling I gather that is used at country-wide scales by policymakers and is an element of several national accounting systems, and real data is gathered by statistic means to characterize the particular economies. There is a dynamic version also.`

@Jesus Lopez - that's very interesting! Is this it? http://www.palermo.edu/ingenieria/pdf2015/15/CyT_15_06.pdf

That might fit nicely into the summer project I mentioned in my intro. Do you have a link for the dynamic version?

`@Jesus Lopez - that's very interesting! Is this it? http://www.palermo.edu/ingenieria/pdf2015/15/CyT_15_06.pdf That might fit nicely into the summer project I mentioned in my intro. Do you have a link for the dynamic version?`

So glad you find it meaningful. Yes, the link is ok, and, while outside of my area of expertice, the dynamic version I'm thinking about is the one used in Computable General Equilibrium, https://en.wikipedia.org/wiki/Computable_general_equilibrium, but I don't know explicit Petri Net treatments in that case.

`So glad you find it meaningful. Yes, the link is ok, and, while outside of my area of expertice, the dynamic version I'm thinking about is the one used in Computable General Equilibrium, https://en.wikipedia.org/wiki/Computable_general_equilibrium, but I don't know explicit Petri Net treatments in that case.`

CGE has gotten a lot of criticism lately from economists like Steve Keene, who is working on his own economic simulation app: https://sourceforge.net/projects/minsky/files/beta builds/

Example criticism: https://yosemite.epa.gov/sab/SABPRODUCT.NSF/9AA0DBDBB259C89985257EDE00703A17/$File/Leamer+comment+10-13-15.pdf

A lot more like it. But Petri Net treatments of macroeconomics would be interesting. Keene's stuff might be a good place to start. I also saw an update of Leontiev lately that I will look for again soon.

`CGE has gotten a lot of criticism lately from economists like Steve Keene, who is working on his own economic simulation app: https://sourceforge.net/projects/minsky/files/beta%20builds/ Example criticism: https://yosemite.epa.gov/sab/SABPRODUCT.NSF/9AA0DBDBB259C89985257EDE00703A17/$File/Leamer+comment+10-13-15.pdf A lot more like it. But Petri Net treatments of macroeconomics would be interesting. Keene's stuff might be a good place to start. I also saw an update of Leontiev lately that I will look for again soon.`

All this is intensely interesting to me. Do you guys know about Jules Hedges' "open games"? I don't, yet, but I gather they're a "compositional" framework where one can build a big miltiplayer game by gluing together smaller "open" games - sorta like what I do with open Petri nets.

`All this is intensely interesting to me. Do you guys know about Jules Hedges' "open games"? I don't, yet, but I gather they're a "compositional" framework where one can build a big miltiplayer game by gluing together smaller "open" games - sorta like what I do with open Petri nets.`

Never heard of Hedges' open games. This? https://julesh.com/2017/09/29/a-first-look-at-open-games/

His intro statement is a little intimidating (to me, anyway): "Even I think open games are hard to understand, and I invented them."

`Never heard of Hedges' open games. This? https://julesh.com/2017/09/29/a-first-look-at-open-games/ His intro statement is a little intimidating (to me, anyway): "Even I think open games are hard to understand, and I invented them."`

@Jesus Lopez: these were a couple of the updates on Leontiev (or rather input-output analysis):

https://en.wikipedia.org/wiki/Environmentally_extended_input-output_analysis

https://en.wikipedia.org/wiki/Material_flow_analysis

I think I can understand the 2nd one better than the first.

(aside: I would love to be able to functionally @mention people in this forum. I think the spaces in names defeats it, but am not sure.

`@Jesus Lopez: these were a couple of the updates on Leontiev (or rather input-output analysis): https://en.wikipedia.org/wiki/Environmentally_extended_input-output_analysis https://en.wikipedia.org/wiki/Material_flow_analysis I think I can understand the 2nd one better than the first. (aside: I would love to be able to functionally @mention people in this forum. I think the spaces in names defeats it, but am not sure.`

My reference for Hedges would be arxiv:1604.06061, to translate Equilibrium there would be sweet! Regarding the io-model, it's a pity that the dynamics is just discrete linear (if I'm not mistaken). A multilinear dyamic system (with its tensor network) would make more use of the ideas of the course. With tensors in the nodes and vectors flowing through the wires, but I don't know of an economic interpretation.

`My reference for Hedges would be arxiv:1604.06061, to translate Equilibrium there would be sweet! Regarding the io-model, it's a pity that the dynamics is just discrete linear (if I'm not mistaken). A multilinear dyamic system (with its tensor network) would make more use of the ideas of the course. With tensors in the nodes and vectors flowing through the wires, but I don't know of an economic interpretation.`

@Jesus - this is a better URL for Steve Keen's Minsky software: https://minsky.sourceforge.io/manual/minsky.html

It at least claims to be dynamic...does it satisfy any of your wishes?

`@Jesus - this is a better URL for Steve Keen's Minsky software: https://minsky.sourceforge.io/manual/minsky.html It at least claims to be dynamic...does it satisfy any of your wishes?`

Well I see there pictures of the Lorenz attractor in your link wich is good! And by the form of the equations in wikipedia for the attractor I think that is a particular case of [1], where we have a multivariate polynomial in the right hand side while the (dynamic and continuous) io-model would be just lineal as in [2]. Perhaps those multiplicative interactions of variables are well described economy-wise somewhere. This case is more interesting dynamically to me with all the chaoticity and bifurcations phenomena described for instance in Prigogine. Interestingly both for contemplation and also to understand and avoid the violent economic phenomena that hitted so hard in countries such as mine. Anyhow let me insist that I'm not particularly knowledgeable in this area, I'm a software engineer. Can you point to a concise and nice source that introduces conceptually game theoretic economic equilibria (assuming some notions of Nash')?

[1] https://golem.ph.utexas.edu/category/2017/07/a_compositional_framework_for_2.html [2] https://link.springer.com/article/10.1007/BF01887911

`Well I see there pictures of the Lorenz attractor in your link wich is good! And by the form of the equations in wikipedia for the attractor I think that is a particular case of [1], where we have a multivariate polynomial in the right hand side while the (dynamic and continuous) io-model would be just lineal as in [2]. Perhaps those multiplicative interactions of variables are well described economy-wise somewhere. This case is more interesting dynamically to me with all the chaoticity and bifurcations phenomena described for instance in Prigogine. Interestingly both for contemplation and also to understand and avoid the violent economic phenomena that hitted so hard in countries such as mine. Anyhow let me insist that I'm not particularly knowledgeable in this area, I'm a software engineer. Can you point to a concise and nice source that introduces conceptually game theoretic economic equilibria (assuming some notions of Nash')? [1] https://golem.ph.utexas.edu/category/2017/07/a_compositional_framework_for_2.html [2] https://link.springer.com/article/10.1007/BF01887911`

Jesus, I don't think economic equilibria exist. At least not for very long. I don't know much about game theory, but http://www.vikwin.de/ does. See https://www.oicos.org/

P.S. Steve Keene was one of the few economists who predicted the 2008 recession.

`Jesus, I don't think economic equilibria exist. At least not for very long. I don't know much about game theory, but http://www.vikwin.de/ does. See https://www.oicos.org/ P.S. Steve Keene was one of the few economists who predicted the 2008 recession.`

Hi all! Pleased to meet you... let me know if I can help in any way.

The 'preferred' introduction paper to open games is https://arxiv.org/abs/1603.04641 . If you don't have the necessary background for it now, you definitely will before the end of this course. The report https://arxiv.org/abs/1604.06061 that @Jesus linked to is written for economists (this is a fairly hopeless thing to do), and is roughly equivalent to reading an introduction to string diagrams mixed with about half of the first paper, followed by slightly more involved economic examples. It carefully doesn't tell you what open games actually

arebecause we thought it would be too scary for the audience.The things you are talking about (like CGE) are

macroeconomics (game theory is micro). With the current setup, I expect (hope?) you can encode it into open games but only by throwing away quite a lot of information. We absolutely plan to head in that direction (I was 'educated' by Viktor Winschel and he is a macroeconomist at heart), and I have vaguely formed ideas about using sheaves to relate micro and macroeconomic models, but this is still quite far away.`Hi all! Pleased to meet you... let me know if I can help in any way. The 'preferred' introduction paper to open games is https://arxiv.org/abs/1603.04641 . If you don't have the necessary background for it now, you definitely will before the end of this course. The report https://arxiv.org/abs/1604.06061 that @Jesus linked to is written for economists (this is a fairly hopeless thing to do), and is roughly equivalent to reading an introduction to string diagrams mixed with about half of the first paper, followed by slightly more involved economic examples. It carefully doesn't tell you what open games actually *are* because we thought it would be too scary for the audience. The things you are talking about (like CGE) are *macro*economics (game theory is micro). With the current setup, I expect (hope?) you can encode it into open games but only by throwing away quite a lot of information. We absolutely plan to head in that direction (I was 'educated' by Viktor Winschel and he is a macroeconomist at heart), and I have vaguely formed ideas about using sheaves to relate micro and macroeconomic models, but this is still quite far away.`

PS. @Bob Be careful about the reasoning "smart iff predicted recession" about economists. There are lots of economists making lots of predictions, and you risk perception bias. Many economists also take the safe option and deny their models have any predictive power, only explanatory.

`PS. @Bob Be careful about the reasoning "smart iff predicted recession" about economists. There are lots of economists making lots of predictions, and you risk perception bias. Many economists also take the safe option and deny their models have any predictive power, only explanatory.`

@Jules Hedges - thank you very much for popping in! I know what you mean about "smart iff predicted recession", but not many predicted that one with numbers and reasons to back them up (not just guessing). Keene and Rubini come to mind. But still, your warning is well advised.

`@Jules Hedges - thank you very much for popping in! I know what you mean about "smart iff predicted recession", but not many predicted that one with numbers and reasons to back them up (not just guessing). Keene and Rubini come to mind. But still, your warning is well advised.`

Re macro and micro: we foolishly plan to try to loop back and forth between micro operational models and somewhat-macro-ish aggregate models later this year. Hoping this class will help. Open games are not on our roadmap, but may be for Jesus. And one of the groups we work with has some game theory fans.

My parent's father and mother were macro-economists. See http://jfaggfoster.org/ They did not have a high opinion of input-output models, though...

`Re macro and micro: we foolishly plan to try to loop back and forth between micro operational models and somewhat-macro-ish aggregate models later this year. Hoping this class will help. Open games are not on our roadmap, but may be for Jesus. And one of the groups we work with has some game theory fans. My parent's father and mother were macro-economists. See http://jfaggfoster.org/ They did not have a high opinion of input-output models, though...`

Handsome to have J. Hedges around. Being an outsider my attitude towards equilibrium is that I need to learn first say classical harmony before start thinking in composing Jazz. Hope to find time to read J. H.'s recent paper.

`Handsome to have J. Hedges around. Being an outsider my attitude towards equilibrium is that I need to learn first say classical harmony before start thinking in composing Jazz. Hope to find time to read J. H.'s recent paper.`

Regarding the meaning of equilibrium in economics, I'm one of the terrible people who says "we do it because it's mathematically convenient". Of course I don't believe that markets settle to general equilibrium in real life, or even that people play Nash equilibria most of the time. But think about physics for example: Even if you have a dynamical system that has some thermal noise input so it can't settle to equilibrium, it's mathematically useful to compute things like eigenstates, as long as you don't claim that your model's equilibrium state is a prediction of what the real world system will do.

`Regarding the meaning of equilibrium in economics, I'm one of the terrible people who says "we do it because it's mathematically convenient". Of course I don't believe that markets settle to general equilibrium in real life, or even that people play Nash equilibria most of the time. But think about physics for example: Even if you have a dynamical system that has some thermal noise input so it can't settle to equilibrium, it's mathematically useful to compute things like eigenstates, as long as you don't claim that your model's equilibrium state is a prediction of what the real world system will do.`

Thanks for the very clear explanation, Jules.

`Thanks for the very clear explanation, Jules.`

Re the ongoing discussions of categories vs UML:

My real goal (and reason for taking this course) is to develop a category theory treatment of this UML diagram: https://valueflows.gitbooks.io/valueflows/specification/diagrams/uml.html

and/or its accompanying RDF-based representation: https://valueflows.gitbooks.io/valueflows/specification/diagrams/vowl.html

The conceptual model is related to Recipes in Chapter 2. Category treatment might best start with the conceptual model, which is currently explained by lots of text and code, slightly inadequate diagrams, and some handwaving.

Jerry Wedekind an instantantiation of this model ~should~ work for printing and transportation systems, too. Might be fun to try.

`Re the ongoing discussions of categories vs UML: My real goal (and reason for taking this course) is to develop a category theory treatment of this UML diagram: https://valueflows.gitbooks.io/valueflows/specification/diagrams/uml.html and/or its accompanying RDF-based representation: https://valueflows.gitbooks.io/valueflows/specification/diagrams/vowl.html The conceptual model is related to Recipes in Chapter 2. Category treatment might best start with the conceptual model, which is currently explained by lots of text and code, slightly inadequate diagrams, and some handwaving. Jerry Wedekind an instantantiation of this model ~should~ work for printing and transportation systems, too. Might be fun to try.`

On the issue of data models, I would like to plug in a couple of ideas with the disclaimer that in some part are not confirmed and would like to hear some feedback on them. Later in the course I hope that we can learn more about Spivak treatment, but now I'd want to note first that there was an old fashioned diagramatic notation, called entity relationship diagram, but that one with diamonds, called "Chen notation" (lots of images in google images), and it would be (as far as I'm correct) the closest notation in the data-modeling space, once adapted and interpreted, to the way that Spivak is modeling. Stetically, one should remove attribute balls, move boxes to just wire labels (so it only remains a net of diamonds), and less trivially give directionality (arrowheads) to the links. This would retain the original data modeling meaning, and it would also correspond (or so I hope) to the string diagrams Spivak talks about.

Note: Today models for relational databases of this kind are seen frequently though they may obscure the paralellism I'm talking about. One notation can be translated into the other easily.

Hope to elaborate further on this as time permits.

`On the issue of data models, I would like to plug in a couple of ideas with the disclaimer that in some part are not confirmed and would like to hear some feedback on them. Later in the course I hope that we can learn more about Spivak treatment, but now I'd want to note first that there was an old fashioned diagramatic notation, called entity relationship diagram, but that one with diamonds, called "Chen notation" (lots of images in google images), and it would be (as far as I'm correct) the closest notation in the data-modeling space, once adapted and interpreted, to the way that Spivak is modeling. Stetically, one should remove attribute balls, move boxes to just wire labels (so it only remains a net of diamonds), and less trivially give directionality (arrowheads) to the links. This would retain the original data modeling meaning, and it would also correspond (or so I hope) to the string diagrams Spivak talks about. Note: Today models for relational databases of [this kind](https://www.altova.com/umodel/uml-database-diagrams) are seen frequently though they may obscure the paralellism I'm talking about. One notation can be translated into the other easily. Hope to elaborate further on this as time permits.`

Jesus, very interesting. The underlying model that we use in valueflows, REA, was designed around 1980 by Bill McCarthy using E-R diagrams, and you can still see one on its wikipedia page

And I am happy to migrate from UML to something better based on Category Theory. We've already migrated to RDF. Always room for one more.

`Jesus, very interesting. The underlying model that we use in valueflows, REA, was designed around 1980 by Bill McCarthy using E-R diagrams, and you can still see one on [its wikipedia page](https://en.wikipedia.org/wiki/Resources,_events,_agents_(accounting_model)) And I am happy to migrate from UML to something better based on Category Theory. We've already migrated to RDF. Always room for one more.`