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In graph Frontier
Computer ScienceData StructuresEstablished

Hash table

In computer science, a hash table is a data structure that implements an associative array, also called a dictionary or simply map; an associative array is an abstract data type that maps keys to values.

Hash tableData structureHash functionArray data structureStackTreeGraph data structureLinked listQueue

At a glance

Type
information
Disciplines 2
Computer ScienceData Structures
Mental models 0
—
Role in the graph
Connector

Key signals

Cross-disciplinary reach
Disciplines
2
  • Computer Science
  • Data Structures
Evidence & development

Dependencies

What this concept builds on and what it makes possible — derived from the atlas’s dependency, causal and structural relations, not from every related edge.

Foundations · builds on

Hash tabledepends onHash functionEstablished

Open Hash function →

hash table depends on hash function.

Mechanism: A hash table uses a hash function to turn a key into an array position, giving near-instant lookups.

Sources:

System context

Hash tableis aData structureEstablished

Open Data structure →

hash table is a kind of data structure.

Mechanism: A hash table is a data structure that maps keys to values via a hash function, giving near-instant lookup by key.

Sources:

Structural role & consequence

Interpreted from the current atlas graph — what the connections mean, not just how many there are.

  • Currently dark in the atlas: 2 of 2 of its relations lack claim-level evidence.

    atlas representation · Describes the current Thinking OS representation, not the state of the world.

  • Builds on 1 foundation (requires / depends-on / derived-from / emerges-from).

    structural · Structural graph analysis — not a claim of importance, causation or history.

  • Structural neighbourhood: 2 → 9 → 22 concepts reachable within 3 hops.

    structural · Structural reach — being reachable is not the same as being understood.

  • All 2 of its relationships stay within its own discipline — a field-specific concept in the current atlas.

    structural · Structural graph analysis — not a claim of importance, causation or history.

0%

cross-field
2 within-field, 0 cross-field

0 of 2 relations carry evidence · concept has a verified source

Strengths & constraints

Constraints

  • Evidence coverage currently thin in the atlas — few of its relationships carry claim-level evidence. atlas representation

Conditions

  • Its dependency reading rests on 1 foundation relation. structural
  • Read structurally — most of its relationships carry no external evidence yet, so claims here are graph-derived. structural

Dependency radial

What this concept builds on (left) and what it makes possible (right) — derived from dependency and causal relations.

Hash functionHash table◀ builds onenables ▶

Seen through each discipline

How this concept sits in each of its fields — derived from its real connections in the graph, not asserted.

Computer Science

Through this lens it connects to Data structure and Hash function.

Hash table through the Computer Science lens →

Data Structures

Through this lens it connects to Data structure.

Hash table through the Data Structures lens →

Key dates

  1. 1953Discoveryhash table: discovery recorded 1953. — Wikidata

Check yourself

A quick check against a common misconception. Nothing is scored — picking the tempting-but-wrong answer just flags an idea worth revisiting.

Which statement is correct?

Common misconceptions

A hash table keeps its items in sorted order.

Hashing scatters keys across the array, so iteration order is effectively arbitrary. If you need order, use a tree-based structure instead.

Look for: Learner expects a hash table to iterate in key order.

Concepts that look related but are not yet connected here — candidates for a connection to reason about, not established links.

Explained by stage
upper secondary

A hash table stores key-value pairs so you can look things up almost instantly. A hash function turns each key into a position in an array, so instead of scanning the whole list you jump straight to where the value lives.

university

A hash table maps keys to array indices via a hash function, giving average O(1) insertion and lookup. Different keys can collide on the same index, so it needs a resolution strategy (chaining or open addressing); performance degrades as it fills, which is why it resizes.

The scientific picture
  • Connects 2 other ideas across 2 disciplines.
  • Most of its connections are of the “Kind & structure” kind.

Derived from the graph’s real structure — observations, not a score.

Sources