🌐 [translation-sync] Add Bivariate Distributions lecture

[mmcky]

Automated Translation Sync

This PR contains automated translations from QuantEcon/lecture-python-intro.

Source PR

#837 - Add Bivariate Distributions lecture

Files Added

• ✅ lectures/bivariate_dist.md
• ✅ .translate/state/bivariate_dist.md.yml

Files Updated

• ✏️ lectures/_toc.yml

Details

• Source Language: en
• Target Language: zh-cn
• Model: claude-sonnet-5

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This PR was created automatically by the translation action.

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✅ Translation Quality Review

Verdict: PASS | Model: claude-sonnet-5 | Date: 2026-08-17
Routing: editor — 1 minor finding(s) in gating categories (accuracy/terminology/syntax/diff-check/other)
Shadow gate: would NOT auto-merge (recorded only; no action taken)

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📝 Translation Quality

Criterion	Score
Accuracy	9/10
Fluency	9/10
Terminology	9/10
Formatting	9/10
Overall	9/10

Summary: 此次新增章节的翻译整体质量很高，准确传达了原文的统计学与概率论概念，术语使用规范并与术语表保持一致，数学公式与代码块格式完整无误，未发现语法错误。仅存在个别措辞可以更精炼的细微建议，不影响整体理解与专业性。 数学公式、代码块与图表标题等结构在翻译中完整保留，未出现格式或语法错误 术语翻译（如“联合分布”“边缘分布”“协方差”“相关系数”“二元正态分布”等）与术语表高度一致，且在全文中保持统一 长句的拆分与重组符合中文表达习惯，逻辑连贯，专业语域把握得当，如对“independence”“covariance”等概念的解释流畅自然

Suggestions:

• [minor · accuracy] lectures/bivariate_dist.md — How joint distributions arise::A common building block, '相关系数完全取决于信号（$a X$）与噪声（$U$）的相对大小。': 全角括号（）与其内部的行内数学公式相邻使用，虽不算错误，但根据格式规范，中文字符与行内代码/公式之间通常需要考虑间距一致性；此处括号内是数学公式，风格上可以接受，但与其他类似位置（如英文原文使用半角括号）相比略有不一致，属于细节问题，不影响理解。
• [minor · fluency] lectures/bivariate_dist.md — Back to the normal distribution::A word of caution, '这与我们上面看到的椭圆形点云毫无相似之处': 译文准确但稍显冗长，可以更精炼地表达“looks nothing like”的语气。 → 可考虑简化为“与我们上面看到的椭圆形点云截然不同”。
• [nit · terminology] lectures/bivariate_dist.md — Preview: regression as a conditional mean: 标题翻译“预告：作为条件均值的回归”准确对应英文，术语与风格与其他章节的“预告”用法一致，无问题，仅作为核实记录。

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🔍 Diff Quality

Check	Status
Scope Correct	✅
Position Correct	✅
Structure Preserved	✅
Heading-map Correct	✅
Overall	10/10

Summary: The translation is a complete, well-structured, and accurately positioned rendering of the new English source document, with correctly formed translation metadata including proper section::subsection notation.

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This review was generated automatically by action-translation review mode.

[Copilot]

Pull request overview

Adds the new “Bivariate Distributions” lecture to the zh-cn lecture set via the automated translation-sync pipeline, and wires it into the Jupyter Book table of contents along with translation state tracking.

Changes:

• Added new translated lecture content: lectures/bivariate_dist.md
• Updated book navigation: lectures/_toc.yml (includes bivariate_dist)
• Added translation sync state metadata: .translate/state/bivariate_dist.md.yml

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
lectures/bivariate_dist.md	New lecture page introducing bivariate distributions, examples, and exercises.
lectures/_toc.yml	Updates book ToC to include the new lecture (and includes additional ToC edits).
.translate/state/bivariate_dist.md.yml	Records translation-sync provenance/state for the new lecture file.

Suppressed comments (2)

lectures/_toc.yml:54

• msy_fishery is referenced in the ToC but the corresponding lecture file does not exist in this repository. This will break the Jupyter Book build/navigation.

  - file: scalar_dynam
  - file: solow
  - file: msy_fishery
  - file: cobweb

lectures/_toc.yml:94

• bayes_intro is referenced in the ToC but the corresponding lecture file does not exist in this repository. This will break the Jupyter Book build/navigation.

  - file: simple_linear_regression
  - file: mle
  - file: bayes_intro
- caption: Other

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[mmcky]

Closing without merge after the 2026-08-19 backlog audit, held on two defect classes caught by byte-comparison against source (both invisible to CI and to review mode, which scored this PR PASS 9.3):

1. Full _toc.yml caption revert — all fourteen translated part captions are reverted to English (导言→Introduction, 经济数据→Economic Data, 基础工具→Foundations, …). This is the lecture-adding-sync defect tracked in Sync overwrites localised _toc.yml part captions with English, and nothing detects it action-translation#254.
2. Untranslated figure captions — the new lecture ships ~17 mystnb caption: values byte-identical to the English source, the class tracked in Figure captions ship untranslated: 74 of 237 on lecture-python.zh-cn across 18 lectures (re-measured 2026-08-20; was 85 of 222) action-translation#255.

Since the whole diff is generated, hand-repairing it here is worse than regenerating: the 2026-08-18 ruling on #254/#255 puts one shared deterministic check (target file must not carry a value byte-identical to source) into the engine's W2 work, and this PR is now the recorded field instance of both surfaces at once.

Re-delivery path: closing this PR means bivariate_dist.md and its .translate/state entry never land, and forward sync refuses missing targets — so this lecture will not arrive on its own; it joins the held set behind the W2 shared check. When the check and caption fix land in the engine, re-deliver via the documented gap-fill (init -f for bivariate_dist) under the then-current engine, which also gets a fresher translation than this v0.25.0 generation. The interim behaviour is fail-closed: source edits to the lecture simply won't sync until the gap-fill runs.