Model Library Overview
The Nexus model library is built on two structured wikis and the Composable Model Schema (CMS v1.2.0) — a machine-readable specification format that enables automated model discovery, code generation, and governance.
Wikis
| Wiki | Entries | Domains |
|---|---|---|
| ABM Wiki | 446 | Finance, epidemiology, supply chain, social systems |
| SD Wiki | 252 | Healthcare, economics, environment, energy, population |
Each entry is structured as a CMS-compliant specification with causal mechanisms, empirical patterns, and parameter guidance. Nexus searches these wikis during the Discover stage of the pipeline.
See CMS & Wiki Reference for the full schema specification and wiki index.
Interactive Diagrams
The examples below are standalone interactive diagrams. They open full-screen at the links provided, and are embedded inline below each description.
ABM Examples
Continuous Double Auction (CDA)
A market microstructure model showing price discovery through order matching. Buyers (10–100) and sellers (10–100) submit limit orders; an order book matches and clears trades. Observables: mid_price, spread, volume, volatility.
Network-Based Systemic Risk Contagion
Bank defaults propagate through a lending network. Topology: directed credit lines between banks. Observables: num_defaults, cascade_depth, systemic_loss.
Multi-Tier Supply Chain — Bullwhip Effect
Order variance amplifies upstream through a four-tier supply chain (Raw Materials → Components → Assembly → Retail). Observables: stock_levels, order_variance, price_volatility.
SD Examples
Exponential Growth (Population)
A single-stock model: Population grows via births = Population × fertility_rate. Pattern: J-curve (unlimited growth). The baseline SD structure for any reinforcing loop.
Aging Population & Healthcare Demand
Four stocks (Young, Working, Elderly_Independent, Elderly_Frail) connected by four feedback loops: R1 Fertility, B1 Mortality, B2 Fiscal, R2 Medical. Pattern: structural deficit when dependency_ratio > 0.7.
Oscillating Business Cycles
Capital stock (plant and equipment) driven by two loops: R1 (Profit → Investment → Capital) and B1 (Capital → Depreciation). Pattern: limit cycle producing boom-bust oscillations.