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Software: explore STEM content (page 15 of 25) · openstem

All fields Software Mathematics Physics Chemistry Biology Engineering Astronomy Environmental Other Software Software groups

Explore STEM Content

Search the community's STEM library — free to study, yours to make your own.

Software

Programming, algorithms and systems on openstem — flashcards, notes, quizzes, sketches and flowcharts shared by the community. Study free, or clone anything into your library.

Content Groups1

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Note~107 words · 1 min

The Pipeline Stages AWS splits CI/CD into three composable services rather than one monolithic tool. CodePipeline orchestrates the stages, CodeBuild compiles and tests, and CodeDeploy rolls the result out to running infrastructure. What Hap

Software

Software · L2 · AWS: CI/CD Pipelines

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Software · L2 · AWS: CI/CD Pipelines

Quiz7 questions

In a 'may' dataflow analysis, how are facts from multiple incoming CFG edges combined at a merge point?

ABy intersection (∩), keeping only facts true on every incoming pathBBy union (∪), keeping facts true on at least one incoming pathCBy discarding all incoming facts and restarting from bottomDBy averaging numeric fact values

Software

Software · L5 · Program Analysis & Abstract Interpretation

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Software · L5 · Program Analysis & Abstract Interpretation

Quiz5 questions

What is a race condition?

AA bug where the outcome depends on the unpredictable timing/interleaving of threads accessing shared stateBAn exception thrown when a thread starts too fastCA compile-time error in multi-threaded codeDA deadlock between two locks

Software

Software · L2 · Java: Concurrency Basics

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Software · L2 · Java: Concurrency Basics

Collection5 items

01Indexes & Query Planning

02Joins & Subqueries

03Data Types & JSONB

+2 more

Software

Software · L2 · PostgreSQL

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Software · L2 · PostgreSQL

Note~113 words · 1 min

From Text to Searchable Tokens A plain `LIKE '%word%'` search can't rank results and can't skip suffixes or grammatical variants. Postgres full-text search instead normalizes text into lexemes — stemmed, lowercased tokens — so 'running' and

Software

Software · L1 · PostgreSQL: Full-Text Search

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Software · L1 · PostgreSQL: Full-Text Search

Collection4 items

01Pattern Fundamentals

02Creational Patterns

03Software · L1 · Design Patterns: Choosing a Creational Pattern

+1 more

Software

Software · L1 · Design Patterns

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Software · L1 · Design Patterns

Collection4 items

01Indexes & Scaling

02Aggregation Framework

03Software · L2 · MongoDB: Replica Sets & Failover

+1 more

Software

Software · L2 · MongoDB

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Software · L2 · MongoDB

Flashcards10 cards

What is Next.js?1 / 10

A React framework for building full-stack web apps. It adds file-based routing, server rendering, data fetching, bundling, and a build/deploy toolchain on top of React.

Software

Next.js Fundamentals

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Next.js Fundamentals

Flowchart10 objects

Software

Software · L2 · If/Then: Making Choices

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Software · L2 · If/Then: Making Choices

Quiz8 questions

What problem does GraphQL's single-endpoint, client-specified query model primarily solve compared to REST?

AIt removes the need for a schemaBOver-fetching and under-fetching, by letting the client ask for exactly the fields it needs in one requestCIt eliminates the need for authenticationDIt guarantees faster network transport than REST

Software

Software · L3 · GraphQL API Design

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Software · L3 · GraphQL API Design

Collection4 items

01Widgets & State

02Dart for Flutter

03Software · L1 · Flutter: Styling & Theming

+1 more

Software

Software · L1 · Flutter

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Software · L1 · Flutter

Quiz5 questions

Why is `counter++` unsafe when called from two threads without synchronization?

AIt is really three steps (read, add, write) that can interleave between threadsBThe `++` operator doesn't exist in most languagesCIntegers can't be shared between threadsDIt only fails on single-core machines

Software

Software · L1 · Concurrency: Protecting Shared State

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Software · L1 · Concurrency: Protecting Shared State

Flashcards10 cards

What problem do generics solve?1 / 10

Generics add compile-time type safety to collections and APIs, eliminating most casts and catching type errors at compile time instead of as runtime ClassCastExceptions. `List<String>` guarantees only Strings go in and come out.

Software

Generics & Exceptions

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Generics & Exceptions

Note~152 words · 1 min

From Credentials to a Trusted Session Every login screen hides a short pipeline: the app takes what a user typed, proves it matches an account, and then hands back something reusable so the user isn't asked to log in on every click. Notice

Software

Software · L1 · Security & Auth: Login & Session Flow

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Software · L1 · Security & Auth: Login & Session Flow

Flashcards10 cards

What exactly does Terraform store in state, beyond a list of resources?1 / 10

A JSON document mapping each resource address to the provider's full attribute snapshot, plus dependency edges, the resource's provider, and a serial/lineage for change tracking. It's the source of truth Terraform diffs against to compute a plan — without it Terraform can't tell what it already manages.

Software

State, Internals & Drift

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State, Internals & Drift

Note~165 words · 1 min

One File, Every Matching Request A `middleware.ts` at the project root runs before a request reaches its matched route — redirecting, rewriting, setting headers/cookies, or gating access based on auth, all before any page or route handler c

Software

Software · L2 · Next.js: Middleware & Edge Runtime

@openstem

Software · L2 · Next.js: Middleware & Edge Runtime

Flashcards10 cards

What does EXPLAIN ANALYZE tell you that EXPLAIN alone does not?1 / 10

`EXPLAIN ANALYZE` actually executes the query and reports actual row counts, actual execution times, and loop counts alongside planner estimates. `EXPLAIN` alone shows only the estimated plan. Discrepancies between estimated and actual rows signal stale statistics.

Software

Query Optimization

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Query Optimization

Note~764 words · 4 min

One-Way Functions: The Minimal Assumption Modern cryptography is built on computational hardness, not information-theoretic secrecy (with the exception of the one-time pad, which requires a key as long as the message). The foundational prim

Software

Software · L5 · Theoretical Cryptography: Hardness, Pseudorandomness, and Proof

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Software · L5 · Theoretical Cryptography: Hardness, Pseudorandomness, and Proof

Flashcards10 cards

What are the four object types in Git's object model?1 / 10

Blob (file contents), tree (directory listing), commit (snapshot pointer with metadata), and tag (annotated tag object).

Software

Internals & Recovery

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Internals & Recovery

Flowchart21 objects

Software

Software · L5 · Distributed Training Architectures

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Software · L5 · Distributed Training Architectures

Flashcards10 cards

What is a JIT compiler and how does V8 use it?1 / 10

A Just-In-Time compiler compiles JS to native machine code at runtime (not ahead of time). V8 initially interprets with Ignition (the bytecode interpreter), then identifies 'hot' functions and compiles them to optimized native code with TurboFan. This gives JS near-native performance on hot paths.

Software

Engine Internals

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Engine Internals

Note~575 words · 3 min

Why Cache at All A cache trades memory for latency: keeping a copy of expensive-to-compute or expensive-to-fetch data somewhere faster to read than the source of truth. The two design questions that matter most are how reads and writes flow

Software

Software · L3 · Caching Strategies

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Software · L3 · Caching Strategies

Collection2 items

01Database & TypeORM

02Authentication & Middleware

Software

Software · L3 · NestJS

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Software · L3 · NestJS

Collection2 items

01Threat Modeling & Zero Trust

02Secure SDLC & Supply-Chain Security

Software

Software · L4 · Security & Auth

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Software · L4 · Security & Auth

Flashcards10 cards

In GKE, what is the difference between Standard and Autopilot modes?1 / 10

Standard mode lets you manage and pay for nodes directly. Autopilot manages nodes for you, billing per-Pod resource requests, reducing operational overhead and enforcing best-practice defaults.

Software

Architecture & Scale

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Architecture & Scale

Flashcards10 cards

What is the TDD cycle?1 / 10

Red-Green-Refactor: write a failing test (red), write minimal code to pass it (green), then refactor while keeping tests green.

Software

TDD & Coverage

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TDD & Coverage

Flowchart7 objects

Software

Software · L2 · AWS: CI/CD Pipelines · flowchart

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Software · L2 · AWS: CI/CD Pipelines · flowchart

Flowchart9 objects

Software

Software · L2 · Binary: 0s and 1s

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Software · L2 · Binary: 0s and 1s

Flashcards10 cards

What do HTTP status code classes 2xx, 3xx, 4xx, 5xx mean?1 / 10

2xx success (200 OK, 201 Created), 3xx redirection (301 Moved, 304 Not Modified), 4xx client error (400 Bad Request, 401 Unauthorized, 404 Not Found), 5xx server error (500 Internal, 503 Unavailable).

Software

HTTP Fundamentals

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HTTP Fundamentals

Quiz6 questions

What is the key structural difference between small-step and big-step operational semantics?

ASmall-step is used only for typed languages; big-step only for untyped languagesBSmall-step defines a single-step relation e → e' composed via →*; big-step defines a direct relation e ⇓ v to the final valueCBig-step semantics can express non-termination directly, small-step cannotDThey differ only in notation and are otherwise formally identical

Software

Software · L5 · Programming Language Semantics

@openstem

Software · L5 · Programming Language Semantics

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