Configuration Variables Along the Phase Space Boundaries for a 2-D CVM Last week’s blog showed how we could get x1 for a specific value of epsilon0, by taking the derivative of the free energy and setting it equal to zero. (This works for the special case where epsilon1 is zero, meaning that there is no interaction enthalpy.) Last week, we looked at one case, where epsilon0 = 1.0. This week, we take a range of epsilon0 values and find…
This Really Is Kind of Obvious, But … There’s something very interesting that we can do to obtain values for the epsilon0 parameter. Let’s stay with the case where there is no interaction enthalpy. In that case, we want to find the epsilon0 value that corresponds to the x1 value at a given free energy minimum. Or conversely, given an epsilon0 value, can we identify the x1 where the free energy minimum occurs? Turns out that, for this…
The 2-D CVM Entropy and Free Energy Minima when the Interaction Enthalpy Is Zero: Today, we transition from deriving the equations for the Cluster Variation Method (CVM) entropies (both 1-D and 2-D) to looking at how these entropies fit into the overall context of a free energy equation. Let’s start with entropy. The truly important thing about entropy is that it gives shape and order to the universe. Now, this may seem odd to those of us who’ve grown…
Why Shifting to the Object-Oriented Coding Approach REALLY IS Important: Well, I hate having to admit it. Mud on my face; all that. But I made a pretty significant Whoops! back this last winter when I posted a “Verification and Validation” document (hah!) to arXiv. The Sad Story of My Previous Ineptitude Well, there’s nothing like hearing about someone else’s screw-up in order to make us feel better about our own life, so here goes. I’d…
The 1-D CVM – A Single Zigzag Chain – Part 1: The cluster variation method (CVM) lets us characterize a system in terms of local patterns, and not just the numbers of units in on/off states. This is likely to be useful for machine learning and AI applications. Up until now, we’ve not told the story of how we actually compute the CVM entropy from the microstates. We’ll do that starting with this post; it will be a handy…
Looking around from a Node’s Point-of-View: As we move from procedural code to object-oriented Python for a Cluster Variation Method (CVM) grid, our perspective shifts. We now need to look at the world from a node’s point-of-view. It’s a lot like updating one’s relationship status in Facebook – except that after updating our own (node) status, we need to not only update the values for all of our own configuration variables, but then we need to travel around the…
The Cluster Variation Method – A Topographic Approach: Object-oriented programming is essential for working with the Cluster Variation Method (CVM), especially if we’re going to insert a CVM layer into a neural network. The reason is that approaching free energy minima via changing node states requires dealing with node, net, and grid topographies. If we’re going to be at all strategic in moving towards free energy minima, then we can’t just pick nodes at random. We need to know…
New Code (Not Released Yet): V&V the Code Before We Play: Well, my darling, as you gathered from last week’s post, the world has shifted. Up until now, when we were talking about having a new free energy function to use inside a neural network, we had to do “Gedankenexperiments” (German for “thought experiments”). Now, though, there’s working code – and I so LOVE seeing the numbers and graphs come out; teasing it, playing with it … stroking it…
Surprising Result Modeling a Simple Scale-Free Brain Network Using the Cluster Variation Method One of the primary research thrusts that I suggested in my recent paper, The Cluster Variation Method: A Primer for Neuroscientists, was that we could use the 2-D Cluster Variation Method (CVM) to model distribution of configuration variables in different brain network topologies. Specifically, I was expecting that the h-value (which measures the interaction enthalpy strength between nodes in a 2-D CVM grid) would change in a…
Single-Parameter Analytic Solution for Modeling Local Pattern Distributions The cluster variation method (CVM) offers a means for the characterization of both 1-D and 2-D local pattern distributions. The paper referenced at the end of this post provides neuroscientists and BCI researchers with a CVM tutorial that will help them to understand how the CVM statistical thermodynamics formulation can model 1-D and 2-D pattern distributions expressing structural and functional dynamics in the brain. The equilibrium distribution of local patterns, or configuration…