A personal knowledge base (PKB) is an electronic tool used by an individual to express, capture, and later retrieve personal knowledge. It differs from a traditional

database In computing, a database is an organized collection of data or a type of data store based on the use of a database management system (DBMS), the software that interacts with end users, applications, and the database itself to capture and a ...

in that it contains subjective material particular to the owner, that others may not agree with nor care about. Importantly, a PKB consists primarily of knowledge, rather than

information Information is an Abstraction, abstract concept that refers to something which has the power Communication, to inform. At the most fundamental level, it pertains to the Interpretation (philosophy), interpretation (perhaps Interpretation (log ...

; in other words, it is not a collection of documents or other sources an individual has encountered, but rather an expression of the distilled knowledge the owner has extracted from those sources or from elsewhere.See also the dissertation of Max Völkel, which examined personal knowledge data models, and proposed a meta-model called "Conceptual Data Structures": The term was mentioned as early as the 1980s, but the term came to prominence in the 2000s when it was described at length in publications by computer scientist Stephen Davies and colleagues, who compared PKBs on a number of different dimensions, the most important of which is the

data model A data model is an abstract model that organizes elements of data and standardizes how they relate to one another and to the properties of real-world entities. For instance, a data model may specify that the data element representing a car be ...

that each PKB uses to organize knowledge.

Data models

Davies and colleagues examined three aspects of the data models of PKBs: * their , which prescribes rules about how knowledge elements can be structured and interrelated (as a

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...

graph Graph may refer to: Mathematics *Graph (discrete mathematics), a structure made of vertices and edges **Graph theory, the study of such graphs and their properties *Graph (topology), a topological space resembling a graph in the sense of discret ...

, tree plus graph, spatially, categorically, as n-ary links, chronologically, or

ZigZag A zigzag is a pattern made up of small corners at variable angles, though constant within the zigzag, tracing a path between two parallel lines; it can be described as both jagged and fairly regular. In geometry, this pattern is described as a ...

); * their , or basic building blocks of information that a user creates and works with, and the level of

granularity Granularity (also called graininess) is the degree to which a material or system is composed of distinguishable pieces, "granules" or "grains" (metaphorically). It can either refer to the extent to which a larger entity is subdivided, or the ...

of those knowledge elements (such as word/concept, phrase/proposition, free text notes, links to information sources, or composite); and * their , which involves the level of formal semantics introduced into the data model (such as a

type system In computer programming, a type system is a logical system comprising a set of rules that assigns a property called a ''type'' (for example, integer, floating point, string) to every '' term'' (a word, phrase, or other set of symbols). Usu ...

and related

schema Schema may refer to: Science and technology * SCHEMA (bioinformatics), an algorithm used in protein engineering * Schema (genetic algorithms), a set of programs or bit strings that have some genotypic similarity * Schema.org, a web markup vocab ...

s, keywords, attribute–value pairs, etc.). Davies and colleagues also emphasized the principle of

transclusion In computer science, transclusion is the inclusion of part or all of an electronic document into one or more other documents by reference via hypertext. Transclusion is usually performed when the referencing document is displayed, and is norma ...

, "the ability to view the same knowledge element (not a copy) in multiple contexts", which they considered to be "pivotal" to an ideal PKB. They concluded, after reviewing many design goals, that the ideal PKB was still to come in the future.

Personal knowledge graph

In their publications on PKBs, Davies and colleagues discussed

knowledge graph In knowledge representation and reasoning, a knowledge graph is a knowledge base that uses a Graph (discrete mathematics), graph-structured data model or topology to represent and operate on data. Knowledge graphs are often used to store interl ...

s as they were implemented in some software of the time. Later, other writers used the term personal knowledge graph (PKG) to refer to a PKB featuring a graph structure and

graph visualization Graph drawing is an area of mathematics and computer science combining methods from geometric graph theory and information visualization to derive two-dimensional depictions of graphs arising from applications such as social network analysis, c ...

. However, the term is also used by software engineers to refer to the different subject of a knowledge graph a person, in contrast to a knowledge graph a person in a PKB.

Software architecture

Davies and colleagues also differentiated PKBs according to their

software architecture Software architecture is the set of structures needed to reason about a software system and the discipline of creating such structures and systems. Each structure comprises software elements, relations among them, and properties of both elements a ...

: file-based, database-based, or client–server systems (including Internet-based systems accessed through desktop computers and/or handheld mobile devices).

History

Non-electronic personal knowledge bases have probably existed in some form for centuries: Leonardo da Vinci's journals and notes are a famous example of the use of

notebook A notebook (also known as a notepad, writing pad, drawing pad, or legal pad) is a book or stack of paper pages that are often ruled and used for purposes such as note-taking, journaling or other writing, drawing, or scrapbooking and more. ...

Commonplace books Commonplace books (or commonplaces) are a way to compile knowledge, usually by writing information into blank books. They have been kept from antiquity, and were kept particularly during the Renaissance and in the nineteenth century. Such book ...

, , annotated

private libraries Private libraries are libraries that are privately owned and are usually intended for the use of a small number of people, or even a single person. As with public libraries, some people use bookplates – stamps, stickers or embossing &nd ...

, and

card file A (German language, German: 'slipbox', plural ) or card file consists of small items of information stored on (German: 'slips'), paper slips or cards, that may be linked to each other through Index term, subject headings or other metadata such ...

s (in German, ) of

index card An index card (or record card in British English and system cards in Australian English) consists of card stock (heavy paper) cut to a standard size, used for recording and storing small amounts of discrete data. A collection of such cards ei ...

s and

edge-notched card Edge-notched cards or edge-punched cards are a system used to store a small amount of binary or logical data on paper index cards, encoded via the presence or absence of notches in the edges of the cards. The notches allow efficient sorting of a l ...

s are examples of formats that have served this function in the pre-electronic age. Undoubtedly the most famous early formulation of an electronic PKB was

Vannevar Bush Vannevar Bush ( ; March 11, 1890 – June 28, 1974) was an American engineer, inventor and science administrator, who during World War II, World War II headed the U.S. Office of Scientific Research and Development (OSRD), through which almo ...

's description of the "

memex A memex (from "memory expansion") is a hypothetical electromechanical device for interacting with microform documents and described in Vannevar Bush's 1945 article " As We May Think". Bush envisioned the memex as a device in which individuals w ...

" in 1945. In a 1962 technical report,

human–computer interaction Human–computer interaction (HCI) is the process through which people operate and engage with computer systems. Research in HCI covers the design and the use of computer technology, which focuses on the interfaces between people (users) and comp ...

pioneer

Douglas Engelbart Douglas Carl Engelbart (January 30, 1925 – July 2, 2013) was an American engineer, inventor, and a pioneer in many aspects of computer science. He is best known for his work on founding the field of human–computer interaction, particularly ...

(who would later become famous for his 1968 "

Mother of All Demos "The Mother of All Demos" was a landmark computer demonstration, named retroactively, of developments by Stanford Research Institute's Augmentation Research Center. It was presented at the Association for Computing Machinery / Institute of Electr ...

" that demonstrated almost all the fundamental elements of modern personal computing) described his use of edge-notched cards to partially model Bush's memex.

Examples

In their 2005 paper, Davies and colleagues mentioned the following, among others, as examples of

software application Application software is any computer program that is intended for end-user use not computer operator, operating, system administration, administering or computer programming, programming the computer. An application (app, application program, sof ...

s that had been used to build PKBs using various data models and architectures: ;

Open source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use and view the source code, design documents, or content of the product. The open source model is a decentrali ...

* Compendium (software) *

Haystack (MIT project) Haystack is a project at the Massachusetts Institute of Technology to research and develop several applications around personal information management and the Semantic Web. The most notable of those applications is the Haystack client, a research ...

NoteCards NoteCards was a hypertext-based personal knowledge base system developed at PARC (company), Xerox PARC by Randall Trigg, Frank Halasz and Thomas Moran in 1984. NoteCards was developed after Trigg's pioneering 1983 Doctor of Philosophy, Ph.D. thes ...

;Closed source *

MyLifeBits MyLifeBits was a life-logging experiment begun in 2001. It is a Microsoft Research project inspired by Vannevar Bush's hypothetical Memex computer system. The project includes full-text search, text and audio annotations, and hyperlinks. The "expe ...

* Personal Knowbase * PersonalBrain * Tinderbox

References

{{Reflist Knowledge representation