# Key Questions Asked by the Duan Yongping Master Perspective: The 9-Point Framework

> Explore the 9 key questions from the Duan Yongping master perspective that drive investment decisions. Learn about business quality, moats, management, and valuation.

- Repository: [Xbt Lin/ai-berkshire](https://github.com/xbtlin/ai-berkshire)
- Tags: architecture
- Published: 2026-07-29

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**The Duan Yongping master perspective codifies nine essential questions—from business quality and moat durability to management integrity and valuation discipline—that drive every investment decision in the ai-berkshire repository’s `dyp-ask` skill.**

The xbtlin/ai-berkshire repository implements the investment philosophy of Duan Yongping (段永平) through a structured decision-making engine called `dyp-ask`. Defined in [`skills/dyp-ask.md`](https://github.com/xbtlin/ai-berkshire/blob/main/skills/dyp-ask.md), this framework distills Duan’s value-investing approach into a repeatable hierarchy of "core thoughts" and "frameworks" that analyze everything from business models to corporate culture, rendered in his distinctive first-person voice using classic phrases like "买股票就是买公司" (buying stocks is buying companies) and "本分" (principled integrity).

## The Nine Core Questions of the Duan Yongping Framework

The Duan Yongping master perspective is built around nine non-negotiable questions that guide every analysis, from quick investment checks to deep-dive company research. These questions are encoded in [`skills/dyp-ask.md`](https://github.com/xbtlin/ai-berkshire/blob/main/skills/dyp-ask.md) and executed sequentially when the skill is invoked.

### 1. What Is the Business?

Duan stresses that a **"great business"** is the starting point for any investment. This question asks whether the company’s core offering creates a durable, repeatable cash-flow engine that can sustain long-term value creation. According to the source code in [`skills/dyp-ask.md`](https://github.com/xbtlin/ai-berkshire/blob/main/skills/dyp-ask.md) (lines 17-27), if the business itself is not great, no amount of cheap valuation can save the investment.

### 2. What Is the Business Model?

Beyond identifying the business, Duan evaluates whether the model exhibits four must-have traits: **differentiation**, a **moat**, **pricing power**, and **low-asset intensity**. As defined in lines 30-36 of [`skills/dyp-ask.md`](https://github.com/xbtlin/ai-berkshire/blob/main/skills/dyp-ask.md), businesses lacking these structural advantages fail the business-model test regardless of current profitability.

### 3. Who Runs the Company?

Management assessment focuses on whether leaders are **"本分"** (principled), aligned with shareholders, and capable of long-term execution. The framework in [`skills/dyp-ask.md`](https://github.com/xbtlin/ai-berkshire/blob/main/skills/dyp-ask.md) (lines 103-108) rejects companies where management lacks integrity or demonstrates poor capital allocation, regardless of operational excellence.

### 4. Is the Company Inside My Ability Circle?

Duan’s **"能力圈"** (ability circle) rule limits investment to companies you can comprehensively comprehend. Lines 62-70 of [`skills/dyp-ask.md`](https://github.com/xbtlin/ai-berkshire/blob/main/skills/dyp-ask.md) mandate that investors must truly understand the company’s products, markets, and competitive risks before committing capital. Violations trigger the "看不懂就不买" (don’t buy what you don’t understand) response.

### 5. What Is the Valuation?

Valuation is treated as a **"毛估估"** (rough estimate) of future cash-flows. According to lines 73-78 of [`skills/dyp-ask.md`](https://github.com/xbtlin/ai-berkshire/blob/main/skills/dyp-ask.md), the price must be below intrinsic value to be attractive, but precision is less important than ensuring a significant margin of safety. Duan prefers "好公司便宜的时候买" (buy good companies when they're cheap).

### 6. What Is the Corporate Culture?

Culture is viewed as a **core moat** that cannot be captured on the balance sheet but drives sustainable advantage. Lines 88-96 of [`skills/dyp-ask.md`](https://github.com/xbtlin/ai-berkshire/blob/main/skills/dyp-ask.md) examine whether the company embodies "本分", user-orientation, and long-term focus. Toxic or short-term cultures disqualify investments immediately.

### 7. What Is the Investment Mindset?

This question examines the investor’s own readiness: Do you possess the patience, discipline, and **"平常心"** (steady mind) to hold the stock for years? Lines 22-30 of [`skills/dyp-ask.md`](https://github.com/xbtlin/ai-berkshire/blob/main/skills/dyp-ask.md) emphasize that without the psychological fortitude to "封仓十年" (seal the position for ten years), even the best analysis fails in execution.

### 8. What Are the "Stop-Doing" Rules?

The **"Stop-doing list"** enumerates actions that must be avoided to preserve capital and integrity. As coded in lines 43-52 of [`skills/dyp-ask.md`](https://github.com/xbtlin/ai-berkshire/blob/main/skills/dyp-ask.md), these include no margin trading, no shorting, and no buying outside your ability circle. Any violation of these hard constraints triggers an automatic rejection.

### 9. What Are the Macro Considerations?

Duan explicitly states he does **not** chase macro-economic forecasts. Lines 12-19 of [`skills/dyp-ask.md`](https://github.com/xbtlin/ai-berkshire/blob/main/skills/dyp-ask.md) establish that good businesses succeed regardless of short-term macro swings, making GDP predictions or interest rate bets irrelevant to the investment decision.

## Technical Implementation in [`skills/dyp-ask.md`](https://github.com/xbtlin/ai-berkshire/blob/main/skills/dyp-ask.md)

The Duan Yongping framework is not merely documentation—it is executable logic. The file [`skills/dyp-ask.md`](https://github.com/xbtlin/ai-berkshire/blob/main/skills/dyp-ask.md) serves as the source of truth, defining the question hierarchy and Duan’s distinctive linguistic patterns (direct, concise, and peppered with his classic catch-phrases).

When parsed by the ai-berkshire engine, the skill maps user queries onto the nine-question framework above. A separate Codex-compatible version is auto-generated at [`codex-skills/dyp-ask/SKILL.md`](https://github.com/xbtlin/ai-berkshire/blob/main/codex-skills/dyp-ask/SKILL.md), allowing the perspective to function within Claude-Code and Codex environments as described in [`AGENTS.md`](https://github.com/xbtlin/ai-berkshire/blob/main/AGENTS.md).

## Invoking the Duan Yongping Perspective

You can activate this framework by calling the `dyp-ask` skill with a JSON payload. The engine parses the query, maps it to the appropriate question blocks, and returns answers in Duan’s first-person voice.

Ask a pure investment question:

```json
{
  "skill": "dyp-ask",
  "prompt": "Should I buy Tencent today?"
}

```

The model runs through all nine core questions—business quality, business model, management, ability-circle, valuation, culture, mindset, stop-doing list, and macro view—ending with a "看不懂就不买" verdict if any rule is violated.

Ask a business-model analysis:

```json
{
  "skill": "dyp-ask",
  "prompt": "What makes the C2M model so valuable?"
}

```

This invocation focuses specifically on the business-model section (differentiation, moat, pricing power, asset lightness) and ties the analysis back to Duan’s principle of buying good companies when they're cheap.

## Summary

The Duan Yongping master perspective in ai-berkshire provides a rigid, repeatable framework for value investing:

- **Nine core questions** cover business quality, model durability, management integrity, circle of competence, valuation discipline, cultural moats, psychological readiness, prohibitions, and macro-agnosticism.
- **Hard constraints** via the Stop-doing list automatically disqualify investments involving margin, shorting, or incomprehensible businesses.
- **Executable logic** resides in [`skills/dyp-ask.md`](https://github.com/xbtlin/ai-berkshire/blob/main/skills/dyp-ask.md), with auto-generated Codex compatibility at [`codex-skills/dyp-ask/SKILL.md`](https://github.com/xbtlin/ai-berkshire/blob/main/codex-skills/dyp-ask/SKILL.md).
- **Linguistic authenticity** ensures responses reflect Duan’s actual voice, using terms like "本分", "毛估估", and "能力圈".

## Frequently Asked Questions

### What does "ability circle" (能力圈) mean in the Duan Yongping framework?

The ability circle is Duan’s principle of limiting investments to businesses you can truly understand. According to [`skills/dyp-ask.md`](https://github.com/xbtlin/ai-berkshire/blob/main/skills/dyp-ask.md) (lines 62-70), if you cannot explain the company’s products, competitive position, and risks in simple terms, the investment falls outside your circle and must be rejected regardless of potential returns.

### How does the `dyp-ask` skill treat macroeconomic analysis?

The framework explicitly ignores macroeconomic forecasting. Lines 12-19 of [`skills/dyp-ask.md`](https://github.com/xbtlin/ai-berkshire/blob/main/skills/dyp-ask.md) state that good businesses succeed regardless of GDP trends or interest rate swings, so the nine questions focus entirely on company-specific factors rather than economic predictions.

### Where is the Duan Yongping perspective implemented in the codebase?

The primary implementation is in [`skills/dyp-ask.md`](https://github.com/xbtlin/ai-berkshire/blob/main/skills/dyp-ask.md), which defines the full question hierarchy and linguistic style. This file is referenced in [`README_EN.md`](https://github.com/xbtlin/ai-berkshire/blob/main/README_EN.md) as one of four value-investing masters, while [`AGENTS.md`](https://github.com/xbtlin/ai-berkshire/blob/main/AGENTS.md) explains how the skill integrates with the repository’s Claude-Code compatibility layer. A generated Codex version exists at [`codex-skills/dyp-ask/SKILL.md`](https://github.com/xbtlin/ai-berkshire/blob/main/codex-skills/dyp-ask/SKILL.md).

### What is "毛估估" (rough estimate) in Duan’s valuation approach?

"毛估估" represents Duan’s insistence on approximate valuation rather than precise spreadsheet modeling. As defined in lines 73-78 of [`skills/dyp-ask.md`](https://github.com/xbtlin/ai-berkshire/blob/main/skills/dyp-ask.md), this means estimating future cash flows roughly to ensure the price offers a clear margin of safety, rather than optimizing for decimal-point accuracy in DCF models.