# Horn clause

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## Definition of the noun Horn Clause

What does Horn Clause mean as a name of something?

**noun**

- [
*logic*] A clause (disjunction of literals) with at most one positive literal.

## Explanation

**Horn clause**: In mathematical logic and logic programming, a Horn clause is a logical formula of a particular rule-like form which gives it good properties for use in logic programming, formal specification, and model theory. Horn clauses are named for the logician Alfred Horn, who first pointed out their significance in 1951, in the article "On sentences which are true of direct unions of algebras", Journal of Symbolic Logic, 16, 14–21.

## Printed dictionaries and other books with definitions for Horn clause

Click on a title to look inside that book (if available):

### Implementation and Application of Automata (2012)

17th International Conference, CIAA 2012, Porto, Portugal, July 17-20, 2012. Proceedings by Nelma Moreira, Rogério Reis

Thus, * a Horn clause is an H1-clause if the term t in the head p*(t) contains at most
one constructor, and no variable occurs twice in t...

* The Horn clause is a normal
clause if it is of the form: p*(f(X1 ,...,X k)) ⇐ p1(Xi1 ),...,p r(Xir),φ where all variables
...

### Universal Algebra for Computer Scientists (2012)

by Wolfgang Wechler

A basic Horn formula is called **a positive Horn clause** if exactly one of its disjuncts
is atomic, whereas * a negative Horn clause is a disjunction of negated atomic
formulas*. A universal Horn sentence p is a universal sentence the matrix of which
...

### Computational Mind: A Complex Dynamics Perspective (2007)

by Vladimir G. Ivancevic, Tijana T. Ivancevic

* A Horn clause is a clause* (a disjunction of literals) with at most one positive
literal.

**A Horn clause**with exactly one positive literal is a definite clause; a Horn clause with no positive literals is sometimes called a goal clause, especially in ...

### Logic for Programming, Artificial Intelligence, and Reasoning (2008)

15th International Conference, LPAR 2008, Doha, Qatar, November 22-27, 2008, Proceedings by Iliano Cervesato, Helmut Veith, Andrei Voronkov

* A definite Horn clause is a logical formula of the form* ∀((u1 ∧...

### Thirteenth Scandinavian Conference on Artificial Intelligence (2015)

SCAI 2015 by S. Nowaczyk

* A Horn clause is a clause with at most one positive literal*. A unit clause is a Horn
clause with exactly one literal. A positive unit clause (sometimes called a fact) is
unit clause with a positive literals. A negative unit clause is a unit clause with a ...

### The Art of Computer Programming, Volume 4A (2014)

Combinatorial Algorithms by Donald E. Knuth

* A Horn clause is an OR of literals in which all or nearly all of the literals are
complemented—at most one of its literals is a pure, unbarred variable*. A Krom
clause is an OR of exactly two literals. Thus, for example, are examples of Horn
clauses; ...

### Algorithmic Learning Theory (1996)

7th International Workshop, ALT '96, Sydney, Australia, October 23 - 25, 1996. Proceedings by Arun K. Sharma, Setsuo Arikawa

* A Horn clause is a clause with at most one positive literal*. CNF
denotes ...

### Practical Aspects of Declarative Languages (2002)

5th International Symposium, PADL 2003, New Orleans, LA, USA, January 13-14, 2003, Proceedings by Veronica Dahl, Philip Wadler

* A Horn clause is a disjunction of one atom* (an atomic predication) and zero or
more negated atoms, though it is more commonly thought of as a conjunction of
zero or more atoms (called the clause body) implying a single atom (the head).

### Advanced Topics in Term Rewriting (2002)

by Enno Ohlebusch

* A Horn clause is a formula of the form A <— B*\ , . . . , Bm where m > 0 and A, B's
are atoms. A logic program P is a finite set of Horn clauses. A goal is a formula of
the form <— B\, . . . , Bm where m > 1 and Bi are atoms. Here only left-to-right ...

### Mathematical Logic for Computer Science (2012)

by Mordechai Ben-Ari

* A Horn clause is a clause that has at most
one positive literal*.

**A fact is a unit Horn clause**with one positive literal; a program ...

### Automata, Languages and Programming (2010)

37th International Colloquium, ICALP 2010, Bordeaux, France, July 6-10, 2010, Proceedings by Samson Abramsky

* A Horn clause is a clause with at most one unnegated variable*. A definite Horn
clause has exactly one unnegated variable, called its head; the other variables
form its body. A negative clause consists of only negated variables. The size of a
...

### Handbook of Proof Theory (1998)

by S.R. Buss

Horn clauses. * A Horn clause is a clause which contains at* ...

### Logic Programming (2004)

20th International Conference, ICLP 2004, Saint-Malo, France, September 6-10, 2004, Proceedings by Bart Demoen, Vladimir Lifschitz

* A Horn clause is a clause with at most one head atom*. The empty clause is
denoted □. An expression is a term, a literal, or a clause. A theory T is a set of
clauses {C1,

### Elements of Computational Systems Biology (2010)

by Huma M. Lodhi, Stephen H. Muggleton

* A Horn clause is a definite
218 INTEGRATING ABDUCTION AND INDUCTION IN BIOLOGICAL
INFERENCE* ...

### Inductive Logic Programming (2013)

22nd International Conference, ILP 2012, Dubrovnik, Croatia, September 16-18,2012, Revised Selected papers by Fabrizio Riguzzi, Filip Zelezny

* A Horn clause is a clause which contains at most
one positive literal; otherwise it is a non-Horn clause*. It is known that a clause is ...

### Proceedings of the First International Conference on Principles of Knowledge Representation and Reasoning (1989)

by Hector J. Levesque

* A Horn clause is a clause in which at most one literal is
unnegated*.

### A Dictionary of Logic (2016)

by Thomas Macaulay Ferguson, Graham Priest

A formula in *conjunctive normal form such that each conjunct is **a
*Horn clause**. hypersequent. A *multiset composed of *sequents introduced by
logician Arnon Avron as a generalization of sequents. Where The punctuation ...

### The International Dictionary of Artificial Intelligence (1999)

by William J. Raynor, William Raynor

**Horn Clause** Logical clauses that have no more than one positive literal.

### Encyclopedia of Machine Learning (2011)

by Claude Sammut, Geoffrey I. Webb

* A Horn clause is a disjunction of literals with at most one positive* (un-negated)
literal; Horn clauses can be further divided into denite clauses, which have one
positive literal, and goal clauses which have none A Prolog program consists of ...

### A Dictionary of Computer Science (2016)

by Andrew Butterfield, Gerard Ekembe Ngondi, Anne Kerr

* A Horn clause is a special case of this general form in that it contains at most one
conclusion*. Horn clauses were first investigated by the logician Alfred Horn. The
majority of formalisms employed in computer programming bear greater ...

### Encyclopedia of Microcomputers (2001)

Volume 27: Supplement 6 by Allen Kent, James G. Williams

**Horn Clause** Logic * A Horn clause is a logical formula of the form A <- B, A B2 A* . .
. A B„, where A, B,, . . . , B„ are terms consisting of symbols but no logical
connectives. A logic program then is just a set of Horn clauses. An important
property of ...

### Blackie’s Dictionary of Computer Science (2013)

by Blackie

**A Horn clause** that has exactly one positive literal. A collection of definite clauses.
defect density deferral definite clause definite sentence A declarative,
programming paradigm which integrates concurrent constraint programming,
constraint ...

### Patrick-Turner's Industrial Automation Dictionary (1996)

by Clarence T. Jones, S. Percy Jones

**Horn clause**: In logic programming, expressions connected by "or" with one
positive proposition in the form "Not A or Not B or Not C or D..." Restricting logical
assertions to horn clauses makes logical programming much more efficient in
much ...

### Dictionary of Computer Science, Engineering and Technology (2000)

by Philip A. Laplante

**Horn clause** also known as a definite clause, it is a clause with one positive literal
. It is written as a disjunction A v -*Bi v . . . v -,Bn or -•61 v...

### Encyclopedia of Operations Research and Management Science (2012)

by Saul I. Gass, Carl M. Harris

One special form is **a Horn clause**. This is where the antecedent is a
conjunction of propositions and the consequent is only one proposition:
P. A. P. A. .

### Encyclopedia of the Sciences of Learning (2011)

by Norbert M. Seel

**A Horn clause** has at most one literal to the left of the implication sign, as in all the
clauses shown above. Such hypotheses correspond to logic programs. Due to
the presence of both the machine learning and logic programming ingredients, ...

### Encyclopaedia of Mathematics, Supplement III (2007)

by Michiel Hazewinkel

**Horn clause** [68T05] (see:
Machine ...

### Wörterbuch der Mikroelektronik und Mikrorechnertechnik mit Erläuterungen / Dictionary of Microelectronics and Microcomputer Technology with Definitions (2013)

by Yvonne H Attiyate, Raymond Shah

**Horn clause** Dlogical programming) Host-Adapterm (SCSI-
Controller für den Anschluß mehrerer Peripheriegeräte an den Rechnerbus)
hostadapter (SCSIcontroller for connecting several peripheral units to computer
bus) ...

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## Video about Horn clause

**Horn clause Meaning**

Video shows what Horn clause means. A clause (disjunction of literals) with at most one positive literal.. Horn clause Meaning. How to pronounce, definition ...

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