Topic: hierarchical structures

topics > philosophy > Group: formalism

file system

abstraction in programming
decomposition of a system into levels
file directory
handling complexity
hierarchical naming
hierarchical structures in hypertext
identifying program modules
knowledge representation
limitations of hierarchical structures
local vs. global
network and hierarchical databases
non-hierarchical classification and multiple classification
recursive data structures
stepwise refinement
structured flow diagram
structured programming
the 'uses' hierarchy for organizing systems
top-down vs. bottom-up design
type hierarchy
using icons to represent windows


Hierarchy is a common method of organizing knowledge, people, and systems. Everything is at some level and linked to elements above and below it in the hierarchy. This reduces complexity since everything can be understood by its location in the hierarchy. There are many visual representations of hierarchies.

Hierarchical organization is widely used in software systems. Technical writing usually follows a hierarchical structure. Control, e.g., of walking, is often hierarchical. (cbb 4/94)

Subtopic: hierarchy for understanding up

Quote: finite automata do not support hierarchical design or concurrency; large, real-time systems are impossible to understand [»benvA9_1991]
Quote: large complex structures are built up step-by-step from simpler structures using discoverable natural laws; includes linguistic structures [»rossDT_1963]

Subtopic: hierarchy as acyclic up

Quote: each context level acts as a single mutex lock and thus prevents cycles in the invocation structure [»maysD5_2002]

Subtopic: hierarchical designs -- 10^9 ratio up

Quote: design hierarchically with repetitive and alternative structures; clear organization, economical, easier debugging and maintenance [»warnJD_1974]
Quote: a programmer must bridge a 10^9 ratio in time and space with a single technology; much deeper conceptual hierarchy than ever before [»dijkEW12_1989]
Quote: each level of a hierarchy represents a doubling or more in size; small and medium systems have few levels [»dijkEW10_1972]

Subtopic: data as hierarchy up

Quote: business data is heterogeneous and hierarchical: fixed-length strings, variable-length strings, and decimal numbers [»glasRL9_1997]
Quote: a typical business report contains labeled columns, identifying strings, and a hierarchy of totals [»glasRL9_1997]
Quote: usually organize documents and files in a hierarchy [»dourP6_1999]

Subtopic: taxonomy as hierarchy up

Quote: a taxonomy is a hierarchy of categories; most abstract is the root [»roscE7_1976]
Quote: define by genus together with successive differentia; e.g., animal that is biped that is featherless [»aris_322a]
Quote: phenomena can be taxonomized in an infinite number of ways at different hierarchical levels; interesting generalizations for each one
Quote: in folk biology, hierarchically classify by life form, generic, specific and varietal; generic largest and defines the fundamental units [»berlB2_1973]

Subtopic: written text as hierarchy up

Quote: readers construct hierarchical representations and remember top levels [»charD11_1987]
Quote: writers should organize text hierarchically, with explicit transitions, and a restricted vocabulary [»charD11_1987]
Quote: with hierarchical organization; users want to operate on subtrees [»akscRM5_1984]
Quote: SGML defines a document as an ordered hierarchy of content objects (OHCO); it does not specify formatting [»deroSJ2_1990]

Subtopic: motor control as hierarchy up

Quote: animal walking control has hierarchical structure and locality of control [»donnMD_1987]
Quote: motor control such as grasping by hierarchically structured schemas [»arbiMA_1987]
Quote: collision control by hierarchical decision making with decision tables [»freuE_1984]

Subtopic: visual representation of hierarchy up

Quote: visual representations of hierarchies: tree, chinese box, outline [»smitJB6_1987]
Quote: tree maps show 2-3 thousand hierarchical nodes by encoding information as a rectangle, with a color and sound; e.g., TreeViz for directories [»shneB1_1993]

Subtopic: UI as hierarchy up

Quote: use hierarchical windows to structure a work environment according to roles [»kandE3_1998]

Subtopic: program as hierarchy up

Quote: determine the hierarchical structure of a program from the input data [»warnJD_1974]
Quote: box containment corresponds to hierarchical structure and part-whole relationships [»diseAA9_1986]
Quote: structured analysis produces a hierarchy of diagrams, each describing a limited area; even complex subjects may be understood [»rossDT1_1977]
Quote: Simula provides a stacking hierarchy of actions, a nesting hierarchy of components, and an inheritance hierarchy of classes [»nygaK10_1983, OK]
Quote: SUIT's composite objects contain any other objects; specify how subobjects get displayed [»pausR10_1992]
Quote: early UNIX systems allowed an arbitrary, directed graph of directories; became too chaotic; even now, multiple links cause problems [»thomK7_1978]
Quote: explore invocation tree with why? to move down tree and then? to show next action [»efeK11_1987]
Quote: a Pygmalion icon acts like a window; has a origin; can form a hierarchical structure with world icon at root [»smitDC6_1975, OK]
Quote: Agenda categories form a hierarchy; items implicitly assigned to their parents [»kaplSJ7_1990]
Quote: if an Agenda category is exclusive, only one sub-category per item; mutual exclusion
Quote: module decomposition produces many small modules; software module guide for completeness, convincing arguments, software maintenance [»parnDL3_1985]

Subtopic: naming as hierarchy up

Quote: relative names allow hierarchical representation of documents; links are independent of the physical or logical location [»bernT8_1994]

Subtopic: numbers as hierarchy up

Quote: easily identify hierarchical relations with symbolic numbers; e.g., if man is 6 and ape is 10 then neither concept contains the other [»leibGW4_1679]

Subtopic: hierarchy as a DAG plus changes up

Quote: Vesta stores directories as a DAG of base pointers plus lists of changes

Subtopic: no parent link up

Quote: no parent links for Vesta directories; allows DAG with shared subdirectories, e.g., a package version and its successor [»heydA_2006]
Quote: a Vesta longid is a 32-byte encoding of a directory path by index number; gives parent directory; never reused

Subtopic: class hierarchy up

Quote: use derived classes to express hierarchical relationships; i.e., commonality between classes

Subtopic: directory hierarchy up

Quote: median directory size is 2 files with 18% containing no files [»doucJR5_1999]
Quote: 69% of all directories have no subdirectories, 16% with one subdirectory, 15% at depth of 8 or greater
Quote: refer to objects via the index of a capability pointing to a directory [»dennJB3_1966]
Quote: a hierarchical directory structure enables passing a subhierarchy to computations and principals
Quote: each principal has a root directory of retained objects

Subtopic: hierarchy not necessary up

Quote: users build elaborate models with spreadsheets; no structure, just a collection of equations

Related Topics up

Group: file system   (9 topics, 305 quotes)
Group: hypertext   (44 topics, 786 quotes)

Topic: abstraction (62 items)
Topic: abstraction in programming (67 items)
Topic: classification (65 items)
Topic: decomposition of a system into levels (49 items)
Topic: file directory (55 items)
Topic: handling complexity (60 items)
Topic: hierarchical naming (28 items)
Topic: hierarchical structures in hypertext (19 items)
Topic: identifying program modules (26 items)
Topic: knowledge representation (41 items)
Topic: limitations of hierarchical structures (10 items)
Topic: local vs. global (29 items)
Topic: network and hierarchical databases (4 items)
Topic: non-hierarchical classification and multiple classification (16 items)
Topic: outlines (16 items)
Topic: recursive data structures (18 items)
Topic: stepwise refinement (25 items)
Topic: structured flow diagram (36 items)
Topic: structured programming (27 items)
Topic: taxonomy (16 items)
Topic: the 'uses' hierarchy for organizing systems (18 items)
Topic: top-down vs. bottom-up design (30 items)
Topic: trees (21 items)
Topic: type hierarchy (18 items)
Topic: using icons to represent windows
(15 items)

Updated barberCB 5/05
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