# 📐  L2 Spec — Extended Kalman Filter (EKF) — Nominal + Mismatch Specs

**ID:** `L2-428-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-428`](/artifact/l1/L1-428)

> **🎯 Tolerance (ε):** expression
> **⚖ Difficulty score:** 0.28 · **Delta tier:** 5
> **⛓ On-chain block:** 41555243

---

## 1. Domain Ω

**Type:** `range`

| Parameter | Unit | Range |
|---|---|---|
| N steps | — | 20 – 5000 |
| Q r ratio | — | 0.01 – 100 |
| N state dim | — | 2 – 20 |
| Nonlinearity degree | — | 0.1 – 3.0 |

## 2. Tolerance (ε)

**Type:** `fn`

```
0.04 + 0.04 * (nonlinearity_degree / 0.5) ** 0.5
```

## 3. Difficulty

| Property | Value |
|---|---|
| Difficulty score | 0.28 |
| Delta tier | 5 |

## 4. Fingerprint

`b83537fd02630126b06ff8d2d85285c5e81d894a05f85c528f776ab985127fd4`

## 5. On-chain Registration

- **Chain hash:** `0x4d2327f676e958a53892e5060eb967274f0aff55e34e373d6f92ce815e1a325e`
- **Chain tx hash:** `0xa2619911eb38118c3f9fa5f5bd993e9f296e2f99227d7df9e1e9e0a4f3359edc`
- **Chain block:** `41555243`

---

## File Mapping

This bundle consists of: `L2-428-001.md`, `L2-428-001.json`.

| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-428-001.md` | Source of truth — edit this | Human or LLM |
| `L2-428-001.json` | Structured metadata for the registry | LLM regenerates from the sections above |

**Prompt for your LLM after editing this Markdown:**

> Read the attached Markdown. Regenerate the sibling `.json` so every field matches.
> Preserve the schema documented in the rows above.
> Output each file in its own fenced code block tagged with the filename.
> Output only the JSON object.

_This Markdown was auto-synthesized from the catalog row for `L2-428-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._