GLOBAL KNOWLEDGE ARK

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Foundations

Explore concepts, laws, equations and methods, with clear explanations of their use and sources. Choose an area of study or find a specific entry.

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Showing 1–30 of 204 reference entries

Physics · Information · MeasurementScientific records

Build an inspectable physics record, test and revise a bounded cart model, preserve processing history, and plan findable data with appropriate sharing conditions.

MethodMathematics & logic · InformationClassical propositions and connectives

Classical logic combines truth-valued propositions using defined connectives.

DefinitionMathematics & logic · InformationSets, membership and basic operations

A set specifies membership without counting duplicate listings.

DefinitionMathematics & logic · InformationFunctions, domain and codomain

A function assigns exactly one output to each input in its domain.

DefinitionMathematics & logic · InformationMathematical induction

A base case and general successor step establish a predicate on all nonnegative integers.

MethodMathematics & logic · InformationComplex numbers

A complex number has real coordinates a and b and an imaginary unit satisfying i²=−1.

DefinitionMathematics & logic · Information · PhysicsLinear maps and matrix representation

A linear map preserves linear combinations and has a matrix once bases are chosen.

DefinitionMathematics & logic · InformationProbability space and axioms

A probability assigns nonnegative, normalised, countably additive weights to events.

DefinitionMathematics & logic · InformationConditional probability and independence

Conditioning restricts attention to an event of positive probability.

DefinitionMathematics & logic · InformationExpected value of a discrete random variable

Expected value weights possible values by their probabilities.

DefinitionInformation · Mathematics & logicBits and unsigned binary encoding

A bit has two possible states; a fixed-width unsigned binary word encodes an integer.

DefinitionInformation · Mathematics & logicShannon entropy of a discrete distribution

Shannon entropy measures uncertainty in a specified probability distribution.

DefinitionInformationAlgorithm and decision procedure

An algorithm specifies effective steps; a decision procedure must terminate on every permitted input.

MethodInformation · Mathematics & logicUndecidability of the halting problem

No total algorithm decides halting for every program and input in a general computation model.

Mathematical statementInformation · Mathematics & logicAsymptotic upper bounds and big O

Big O bounds eventual growth up to a fixed constant factor.

DefinitionInformationFinite-alphabet mutual information

Mutual information measures statistical dependence in bits.

DefinitionInformationNear-lossless source coding threshold

Entropy bounds asymptotic compression for an iid source.

Mathematical statementInformationDiscrete memoryless channel capacity

Capacity is the maximal asymptotically reliable rate.

Mathematical statementInformationHamming distance and error correction

Separated codewords permit bounded symbol-error recovery.

Mathematical statementInformationInternet protocol layers

Protocol layers divide communication responsibilities.

DefinitionInformationTCP reliable byte-stream transport

TCP orders bytes and retransmits detected losses.

MethodInformationEncryption, hashes and message authentication

Cryptographic primitives serve distinct security properties.

DefinitionInformationPublic-key digital signatures

A signing key and a verification key have different roles.

DefinitionInformationComputable reductions and undecidability

Reduction direction determines which impossibility transfers.

Mathematical statementInformationDecision classes P and NP

Polynomial solving and polynomial verification differ.

DefinitionInformationNP-hardness and NP-completeness

NP-completeness combines verification and reduction hardness.

DefinitionInformationBounded-error randomized computation

Random choices permit a stated probability of error.

DefinitionInformationFinite graphs and trees

Graphs represent pairwise connections; trees impose acyclicity.

DefinitionInformationData-structure interfaces and operation costs

An interface defines operations; an implementation determines costs.

MethodInformationLoop invariants and total correctness

An invariant establishes correctness only with its proof obligations.

Method
DefinitionSource checked

Internet protocol layers

Information

Protocol layers divide communication responsibilities.

Key knowledge

The Internet architecture distinguishes application, transport, internet and link layers. Application protocols serve applications; transport provides end-to-end service; IP carries datagrams across networks; link protocols communicate on a directly connected network.

Conditions and scope

  • This is the four-layer Internet convention, distinct from the OSI model.
  • A layer boundary is an architectural abstraction, not a guarantee of delivery or security.
Sources · 1

References

Sources retain their recorded scope. A source link alone does not establish verification of every statement.

  1. RFC 1122, section 1.1.3IETF / RFC EditorReference guiderfc-editor.orgRead source

Evidence and review

Application, transport, internet and link layer roles; historical architecture only, not obsolete deployment advice.

2026-10-10 · RFC 1122 section 1.1.3 layer roles only.

Related reference entries

Explore relationships within this area of study and its connections to other areas.

Showing 1–3 of 3 relationships

Scientific relationships · 3 / 3

The relationship type describes the connection. Its linked statements, sources and conditions define the scope.

  1. Uses definition
    Relationship sources · 1

    Linked statements

    • TCP provides a connection-oriented, in-order byte stream using sequence numbers, per-segment checksums and retransmission. Application write boundaries need not correspond to received segment or read boundaries.
  2. Related to
    Relationship sources · 4

    Linked statements

    • Crash faults stop a process; Byzantine faults permit arbitrary behavior, including inconsistent messages. Synchronous models assume timing bounds, asynchronous models do not, and partial synchrony supplies bounds after an unknown stabilization time or unknown finite bounds. Safety forbids an incorrect result; liveness requires eventual progress in allowed runs. A timeout can suspect a slow process but cannot distinguish delay from failure in a fully asynchronous model.

    Local transport guarantees do not supply an end-to-end timing/fault model.

  3. Uses definition
    Relationship sources · 1

    Linked statements

    • IPv4 source and destination addresses are 32 bits. IPv6 addresses are 128-bit identifiers for interfaces or sets of interfaces. IP provides connectionless datagram service without end-to-end delivery guarantees; packets may be lost, duplicated or reordered.

    IP provides Internet-layer datagrams; reliable transport is a separate layer's role.

Entry detailsPermanent link to this entry ↗
Record identity
info-protocol-layering
Revision
university-reference.1
Structured reference record
University reference