brain

tamnd's digital brain — notes, problems, research

41968 notes

稳健 (wěnjiàn) — steady and sound; prudent

HSK 5 | adjective | firm and well-grounded; not reckless or volatile

hsk-5vocabularyb2
想 (xiǎng) — to want to; to think; to miss

HSK 1 | verb | expresses desire, thought, and longing

hsk-1vocabularya1
Lesson 25: Negation

All Sindarin negation forms: ú- prefix, avo imperative negation, baw prohibition, and law/lav forms — with attested examples and contextual usage.

sindaringrammarnegationintermediate
咖啡 (kāfēi) — coffee

HSK 1 | noun | coffee

hsk-1vocabularya1
论据 (lùnjù) — evidence, grounds

HSK 6 | n | facts, examples, or reasoning used to support an argument

hsk-6vocabularyc1
特别 (tèbié) — special / especially

HSK 3 | adjective / adverb | special, particular; especially, particularly

hsk-3vocabularya2
篇 (piān) — piece of writing; article (measure word)

HSK 2 | measure word | counts complete pieces of written or composed work

hsk-2vocabularya1
融资 (róngzī) — to raise funds; financing

HSK 5 | verb / noun | to raise capital; the act of financing

hsk-5vocabularyb2
项目 (xiàngmù) — project / item

HSK 3 | noun | a project or planned undertaking; a listed item or entry

hsk-3vocabularya2
检查 (jiǎnchá) — to check / examine

HSK 3 | verb | to check, to inspect, to examine — used for medical or general review

hsk-3vocabularya2
照顾 (zhàogù) — to take care of

HSK 3 | verb | to look after, take care of, or attend to someone's needs

hsk-3vocabularya2
辩论 (biànlùn) — to debate; a debate

HSK 5 | verb / noun | to argue opposing sides; formal debate

hsk-5vocabularyb2
报名 (bàomíng) — to register / sign up

HSK 3 | verb | to register, to sign up, to enroll

hsk-3vocabularya2
Lesson 7: Dependent Clauses

Learn to build complex sentences using subordinating conjunctions: ke, ĉar, kvankam, se, kiam, por ke, and indirect questions.

esperantob1lesson
另外 (lìngwài) — in addition; besides; additionally

HSK 4 | adverb/conjunction | introducing additional information

hsk-4vocabularyb1
明白 (míngbai) — to understand / clear

HSK 3 | verb / adjective | to understand, to be clear about something

hsk-3vocabularya2
出口 (chūkǒu) — export; exit

HSK 5 | noun/verb | to export goods; an exit or way out

hsk-5vocabularyb2
观点 (guāndiǎn) — viewpoint; standpoint; perspective

HSK 3 | noun | one's particular way of seeing or interpreting something

hsk-3vocabularya2
选择 (xuǎnzé) — to choose; to select; choice

HSK 4 | verb/noun | the act of choosing or a choice made

hsk-4vocabularyb1
Lesson 12: Hobbies and Free Time

Learn to talk about your hobbies, ask yes/no questions, and use the -ad- suffix for ongoing activities.

esperantoa1lesson
〜ば — Japanese Grammar

〜ば: JLPT N4 grammar pattern. Usage, structure, examples, and comparison with similar patterns.

japanesegrammarn4conditional
能力 (nénglì) — ability; capability

HSK 5 | noun | ability, capability, capacity to do something

hsk-5vocabularyb2
Lesson 26: The Verb To Be — na-

Complete treatment of Sindarin na- (to be): present nâ, past nant, future natha, imperative no, and predicative adjective construction.

sindaringrammarverbscopulaintermediate
N4 Kanji: 図 (Diagram, Map, Plan)

JLPT N4 kanji 図 — readings, vocabulary, stroke order, mnemonic, and common confusion pairs.

japanesen4jlptkanjilanguage-learning
Lesson 7: Imperfect and Future Tense Active

Form and use the imperfect (ongoing past) and future tenses for all four conjugations and esse.

latinnovicelesson
论坛 (lùntán) — forum

HSK 5 | noun | a public forum for discussion; an online discussion board

hsk-5vocabularyb2
从来 (cónglái) — never / always (with negation)

HSK 3 | adverb | used with negation to mean 'never' or 'not once'

hsk-3vocabularya2
Lesson 10: Hobbies and Free Time

Learn to talk about what you like doing and what skills you have using 喜欢 and 会.

hsk-1lessona1
あります / います — Existence of Things and Beings
japanesegrammarn5existence
Lesson 18: Historical Narrative

The conventions of Chinese historical writing — 历史叙述 style, evaluative vocabulary, and the language of historical significance and controversy

hsk-6lessonc1
政策 (zhèngcè) — policy

HSK 5 | noun | an official plan or course of action adopted by a government or organization

hsk-5vocabularyb2
担任 (dānrèn) — to serve as; to hold (a position)

HSK 4 | verb | officially occupying a role or post

hsk-4vocabularyb1
口 (kǒu) — mouth / measure word for mouths and bites

HSK 1 | noun / measure word | mouth, opening, bite-sized portions

hsk-1vocabularya1
总结 (zǒngjié) — summary / to summarize

HSK 3 | noun / verb | summary, conclusion; to summarize, to wrap up

hsk-3vocabularya2
深入 (shēnrù) — in-depth; thorough; penetrating

HSK 4 | adjective / verb | thorough and deep; to go deep into something

hsk-4vocabularyb1
杯 (bēi) — measure word for cups and glasses

HSK 1 | measure word | classifier for cups, glasses, and their contents

hsk-1vocabularya1
确认 (quèrèn) — to confirm; to verify

HSK 5 | verb | to confirm; to acknowledge as correct

hsk-5vocabularyb2
〜と — And; With (Accompaniment)
japanesegrammarn5particles
倡议 (chàngyì) — initiative; proposal; to propose

HSK 5 | noun/verb | initiative; proposal; to put forward a proposal or call to action

hsk-5vocabularyb2
JLPT N5 Lesson 8: Describing with Adjectives

Master the two types of Japanese adjectives to describe people, places, and things with precision and natural flair.

japanesen5lessonjlpt
Lesson 4: Advanced Participle Nuance

A rigorous analysis of Esperanto's participial system — the -ata/-ita controversy, compound tenses, participial nouns, and verbal adjectives with full semantic precision.

esperantoc1lesson
广告 (guǎnggào) — advertisement; commercial; ad

HSK 3 | noun | a public announcement promoting a product or service

hsk-3vocabularya2
形象 (xíngxiàng) — image; figure; vivid

HSK 5 | noun/adjective | a person or organization's public image; also vivid/concrete representation

hsk-5vocabularyb2
义务 (yìwù) — duty; obligation

HSK 5 | noun | duty; obligation; obligatory service

hsk-5vocabularyb2
准备 (zhǔnbèi) — to prepare

HSK 3 | verb | to prepare, get ready, or plan to do something

hsk-3vocabularya2
总而言之 (zǒng ér yán zhī) — in summary; in short; to sum up

HSK 5 | discourse marker | in summary; in short; to sum up

hsk-5vocabularyb2
自然 (しぜん) — Japanese Vocabulary

自然 (しぜん / shizen): nature. N4 level Japanese vocabulary.

japanesevocabularyn4noun
应用程序 (yìngyòng chéngxù) — application, app

HSK 4 | noun | a software application designed for a specific purpose

hsk-4vocabularyb1
乘 (chéng) — to ride; to take (transport)

HSK 3 | verb | to board or travel by a vehicle

hsk-3vocabularya2
词语 (cíyǔ) — word; phrase; expression

HSK 3 | noun | a word or short phrase in Chinese

hsk-3vocabularya2
Numbers & Mathematics

Esperanto numbers, counting, arithmetic, ordinals, fractions, and mathematical vocabulary.

esperantovocabularynumbersmathematicscounting
面条 (miàntiáo) — noodles

HSK 2 | noun | noodles, a staple food made from wheat flour

hsk-2vocabularya1
也 (yě) — also, too

HSK 1 | adverb | also, too — adds the same information about the subject

hsk-1vocabularya1
中 — JLPT N5 Kanji

中 (chuu/naka): inside. JLPT N5 kanji.

japanesekanjin5jlpt
改变 (gǎibiàn) — to change; to alter; change

HSK 4 | verb / noun | making or experiencing a shift in condition or nature

hsk-4vocabularyb1
收 (shōu) — to receive / collect

HSK 3 | verb | to receive, to collect, to put away

hsk-3vocabularya2
Lesson 16: Possessive Pronouns

Sindarin possessive pronouns: suffix forms attached to nouns, independent possessive forms, and the genitive construction with en.

sindaringrammarpronounspossessivesintermediate
背景 (bèijǐng) — background; backdrop

HSK 5 | noun | background, backdrop, context, personal connections

hsk-5vocabularyb2
越来越… (yuè lái yuè...) — more and more...

HSK 3 | grammar pattern | describes a quality that keeps intensifying over time

hsk-3vocabularya2grammar
推出 (tuīchū) — to launch; to roll out

HSK 5 | verb | to launch; to introduce; to put forward

hsk-5vocabularyb2
N4 Kanji: 教 (Teach, Instruct)

JLPT N4 kanji 教 — readings, vocabulary, stroke order, mnemonic, and common confusion pairs.

japanesen4jlptkanjilanguage-learning
〜をめぐって / 〜をめぐる — JLPT N2 Grammar

Learn 〜をめぐって and 〜をめぐる to discuss debates, controversies, and disputes surrounding a topic in formal Japanese.

japanesegrammarn2jlpt
经济 (jīngjì) — economy; economic

HSK 5 | noun/adjective | economy, economics; economical, affordable

hsk-5vocabularyb2
CF 472D - Design Tutorial: Inverse the Problem

We are given an $n times n$ matrix where each entry $d[i][j]$ represents the distance between nodes $i$ and $j$. The question asks whether there exists a weighted tree with $n$ nodes such that the distance along the tree between any two nodes exactly matches the corresponding…

codeforcescompetitive-programmingdfs-and-similardsushortest-pathstrees
三 — JLPT N5 Kanji

三 (san/mit-tsu): three. JLPT N5 kanji.

japanesekanjin5jlpt
JLPT N5 — Kanji (All 103)

Complete list of all 103 JLPT N5 kanji with stroke count, on-yomi, kun-yomi, meaning, and example words.

japanesejlptjlpt-n5kanjilanguage-learning
提升 (tíshēng) — to improve; to upgrade; to promote

HSK 4 | verb | to raise something to a higher level or quality

hsk-4vocabularyb1
根据 (gēnjù) — according to; based on; basis

HSK 4 | preposition / noun | using something as a foundation or source

hsk-4vocabularyb1
减少 (jiǎnshǎo) — to reduce / to decrease

HSK 3 | verb | to make something smaller in amount or number

hsk-3vocabularya2
规律 (guīlǜ) — law, pattern, regularity

HSK 5 | noun | regular, predictable pattern or law governing phenomena

hsk-5vocabularyb2
Supplement 1: Historical Phonology — How Sindarin Evolved

The complete sound change history from Primitive Elvish through Common Telerin and Old Sindarin to Classical Sindarin — explaining WHY mutations exist and how the vowel system developed.

sindarinhistorical-phonologyetymologymutationsadvanced
偏见 (piānjiàn) — prejudice, bias

HSK 5 | noun | an unfair preconceived opinion not based on reason or experience

hsk-5vocabularyb2
Lesson 17: Comparison of Adjectives and Adverbs

Regular and irregular comparative and superlative adjectives, formation of comparative and superlative adverbs, and ablative of comparison vs. quam.

latinnovicelesson
投入 (tóurù) — to invest; to put into; input; absorbed

HSK 5 | verb/noun/adjective | to put in effort or resources; input; deeply absorbed

hsk-5vocabularyb2
代码 (dàimǎ) — code; source code

HSK 5 | noun | code; source code; programming code

hsk-5vocabularyb2
Supplement 2: Complete Verb Paradigm Reference

Master reference for all Sindarin verb conjugation: all 12 verb classes, all tenses/moods, all 9 persons — with full tables for model verbs and notes on scholarly disagreements.

sindaringrammarverbsreferenceadvanced
再 (zài) — again (future), then, more

HSK 2 | adverb | again (future repetition), then, one more time

hsk-2vocabularya1
Lesson 2: Correlatives — ki-, ti-, i-

Learn the systematic ki- (question), ti- (demonstrative), and i- (indefinite) correlative series in Esperanto.

esperantoa2lesson
〜のもとで / 〜のもとに — JLPT N2 Grammar

Learn 〜のもとで and 〜のもとに to express acting under conditions, authority, supervision, or established premises.

japanesegrammarn2jlpt
北 — JLPT N5 Kanji

北 (ホク/きた): north. JLPT N5 essential kanji.

japanesekanjin5jlpt
生态 (shēngtài) — ecology; ecological

HSK 5 | noun/adjective | the relationship between living organisms and their environment

hsk-5vocabularyb2
表明 (biǎomíng) — to indicate; to make clear; to show

HSK 4 | verb | to clearly express or demonstrate something

hsk-4vocabularyb1
生气 (shēng qì) — to get angry, angry

HSK 2 | verb/adjective | to get angry, to be angry

hsk-2vocabularya1
留 (liú) — to stay / to leave behind

HSK 3 | verb | to stay, to remain; to leave behind, to keep; to leave a message

hsk-3vocabularya2
评论 (pínglùn) — to comment; commentary

HSK 5 | verb / noun | to comment or critique; a commentary or review

hsk-5vocabularyb2
对 (duì) — correct / towards

HSK 1 | adjective / preposition | correct, right; directed at, towards

hsk-1vocabularya1
疫苗 (yìmiáo) — vaccine

HSK 5 | noun | a biological preparation used to provide immunity against a disease

hsk-5vocabularyb2
表述 (biǎoshù) — to describe, to formulate

HSK 6 | verb | to express or articulate ideas clearly and systematically

hsk-6vocabularyc1
盐 (yán) — salt

HSK 3 | noun | salt, the common cooking mineral

hsk-3vocabularya2
之前 (zhīqián) — before; prior to

HSK 3 | adverb | indicates that something happens before a specific event or time

hsk-3vocabularya2
哪怕 (nǎpà) — even if; no matter

HSK 5 | conjunction | even if, even though, no matter (strong concession)

hsk-5vocabularyb2
冷静 (lěngjìng) — calm; cool-headed; composed

HSK 3 | adjective | remaining rational and unruffled in difficult situations

hsk-3vocabularya2
书 (shū) — book

HSK 1 | noun | book

hsk-1vocabularya1
六 — JLPT N5 Kanji

六 (roku/mut-tsu): six. JLPT N5 kanji.

japanesekanjin5jlpt
方式 (fāngshì) — Method

HSK 4 | noun | method, way, manner, mode

hsk-4vocabularyb1
它 (tā) — it

HSK 1 | pronoun | third-person singular pronoun for non-human things

hsk-1vocabularya1
肚子 (dùzi) — belly / stomach

HSK 3 | noun | belly, stomach, abdomen (colloquial)

hsk-3vocabularya2
管理 (guǎnlǐ) — management; to manage

HSK 5 | verb/noun | to manage, administer, or oversee; management

hsk-5vocabularyb2
动词+得+adj — verb + degree complement

HSK 3 | grammar pattern | describes how well or intensely an action is performed

hsk-3vocabularya2grammar
利用 (lìyòng) — to use; to make use of; to utilize

HSK 4 | verb | to take advantage of something for a purpose

hsk-4vocabularyb1