assembly-economics/models/GADM-0.4.md
tegwick ee7b17da5e ASSEMBLY-WP-0006-T02: ground organism depreciation, robustness checks
- dO grounded at 0.20/yr (software, R&D capital, AI hardware evidence);
  investment/learning rescaled so the baseline organism path is unchanged
- robustness.py: key readings hold for grounded dO and brackets on channel
  self-reinforcement and wealth conversion; P3 effect size grows at strong
  self-reinforcement
- models/ParameterGrounding.md: register of grounded / bracketed / assumed /
  calibrated parameters, open grounding needs

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

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2026-10-12 08:27:08 +02:00

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<!--
Created 2026-10-12 under ASSEMBLY-WP-0006. Sections are added as the
GADM-0.4 tasks are completed. Implemented by simulations/gadm02/gadm04.py;
the code is the reference if the two ever disagree.
-->
# Generative Assembly Dynamics Model — GADM-0.4
**Status:** in development, exploratory. Implemented so far: durable human
capability (§ 1, ASSEMBLY-WP-0006-T01), grounded organism depreciation and
robustness checks (§ 2, T02).
GADM-0.4 builds on the GADM-0.3 cohort model (`GADM-0.3.md` § 5), which stays
unchanged and reproducible in `gadm03c.py`. Time unit: one year.
---
## 1. Durable human capability (T01)
### 1.1 Motivation
GADM-0.3 failed hypothesis L3: an education push reached working-age
capability after only about 9 years, and weakly. Working-age capability had no
memory of childhood, because it relaxed to current conditions within about 8
years.
### 1.2 Structure
Each cohort's capability is split into:
| Component | Formed by | Depreciation (per year) | Carried by ageing |
|---|---|---|---|
| **durable D_c** | education in childhood (`hform`, scaled by `edu`, plus commons X); small lifelong formation for adults (`ll`) | 0.01 (children, working age), 0.02 (seniors), 0.04 (very old) | yes |
| **current C_c** | GADM-0.3 cohort dynamics (learning, mentoring, deskilling, care) | as GADM-0.3 | yes |
Effective cohort capability: \(H_c = \tfrac12 D_c + \tfrac12 C_c\). Aggregate H,
which the rest of the model uses, is population-weighted as in GADM-0.3.
Two couplings:
- **Learning begets learning:** a cohort's current-capability gains are
scaled by \(1 + lbl\,(D_c - 0.5)\).
- **Birth dilution:** newborns enter the children's cohort with no durable
capability, so the cohort average is diluted at the birth rate (about 1/20
per year). A first draft omitted this term; durable capability then
saturated near 0.85, leaving no room for an education effect.
Initial values: D_c = C_c = GADM-0.3 H_c, so effective capability starts
identical to GADM-0.3 (unit-tested).
### 1.3 Results
Computed at T01, before `dO` was grounded (§ 2). The grounded values differ
by at most 0.004.
| | GADM-0.3 cohorts | GADM-0.4 |
|---|---|---|
| Baseline VFAC (t = 100) | 0.323 | 0.323 |
| Generative regime VFAC | 0.656 | 0.661 |
| L3: education +50 % → final ΔH working age | +0.010 | **+0.032** |
| L3: years to half of that effect | 9 | **17** (durable part: 21) |
| L1: ageing + strong mentoring (tg 0.15), ΔH | −0.018 | −0.029 |
| L1: stable, no mentoring, ΔH | −0.043 | −0.039 |
Full tables: `simulations/gadm02/results/life_cycle_gadm04.md`.
### 1.4 Readings
1. **L3 is now supported.** Education reaches working-age capability with a
17-year half-time, inside the hypothesised 15–20 years, and with three
times the effect. The lag comes from cohort turnover (about 2.2 % per year)
plus slow durable depreciation. The relaxation time is about
1/(0.01 + 0.022) ≈ 30 years.
2. **L1 still holds, more weakly.** Mentoring acts on current capability
only, so its leverage on effective capability halves. An ageing society
with strong mentoring still loses less than a stable society without it.
3. **Macro results are almost unchanged.** Durable capability adds memory,
not level: baseline and generative VFAC move by at most 0.005. Policies on
education matter mostly beyond a 20-year horizon, which strengthens the
case for longer simulation horizons in cohort experiments.
### 1.5 Limitations
- The split ½ / ½ between durable and current capability is assumed.
- Children's *current* capability (inherited from GADM-0.3) still has no
birth dilution. Only the durable component was corrected.
- `hform` was chosen so that baseline children's durable capability settles
near 0.6. It has no empirical anchor yet (see T02).
---
## 2. Parameter grounding (T02)
Details and sources: `ParameterGrounding.md`.
- **Organism depreciation is grounded:** `dO` = 0.20 per year (evidence range
0.15–0.35, from software, R&D-capital and AI-hardware depreciation), instead
of 0.06. Investment, learning and seeding are rescaled (×3.33) so the
baseline organism path is unchanged. The evidence changes the timescale;
the level of organism capability remains ungrounded.
- **The key readings are robust** to the grounded `dO` and to brackets on the
ungrounded channel self-reinforcement (0.15–0.45) and wealth conversion
(0.02–0.20). One exception: P3's effect size grows to −0.078 at strong
self-reinforcement.
- With grounded `dO`: baseline VFAC 0.325, generative regime 0.665. The life-cycle results
are essentially unchanged: L3 half-time 17 years, final ΔH working age +0.032;
L1 ΔH −0.028 (ageing, strong mentoring) against −0.038 (stable, none).
## Reproduce
```bash
python3 -B -m unittest discover -s simulations/gadm02
cd simulations/gadm02 && python3 -B life_cycle.py --model gadm04
cd simulations/gadm02 && python3 -B robustness.py # T02 robustness checks
```