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|  |      2 | <HTML><HEAD><TITLE>HOL/Algebra/README.html</TITLE></HEAD><BODY>
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|  |      4 | <H2>Algebra: Theories of Rings and Polynomials</H2>
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|  |      5 | 
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|  |      6 | <P>This development of univariate polynomials is separated into an
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|  |      7 | abstract development of rings and the development of polynomials
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|  |      8 | itself. The formalisation is based on [Jacobson1985], and polynomials
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|  |      9 | have a sparse, mathematical representation. These theories were
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|  |     10 | developed as a base for the integration of a computer algebra system
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|  |     11 | to Isabelle [Ballarin1999], and was designed to match implementations
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|  |     12 | of these domains in some typed computer algebra systems.  Summary:
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|  |     13 | 
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|  |     14 | <P><EM>Rings:</EM>
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|  |     15 |   Classes of rings are represented by axiomatic type classes. The
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|  |     16 |   following are available:
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|  |     17 | 
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|  |     18 | <PRE>
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|  |     19 |   ringS:	Syntactic class
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|  |     20 |   ring:		Commutative rings with one (including a summation
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|  |     21 | 		operator, which is needed for the polynomials)
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|  |     22 |   domain:	Integral domains
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|  |     23 |   factorial:	Factorial domains (divisor chain condition is missing)
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|  |     24 |   pid:		Principal ideal domains
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|  |     25 |   field:	Fields
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|  |     26 | </PRE>
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|  |     27 | 
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|  |     28 |   Also, some facts about ring homomorphisms and ideals are mechanised.
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|  |     29 | 
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|  |     30 | <P><EM>Polynomials:</EM>
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|  |     31 |   Polynomials have a natural, mathematical representation. Facts about
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|  |     32 |   the following topics are provided:
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|  |     33 | 
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|  |     34 | <MENU>
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|  |     35 | <LI>Degree function
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|  |     36 | <LI> Universal Property, evaluation homomorphism
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|  |     37 | <LI>Long division (existence and uniqueness)
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|  |     38 | <LI>Polynomials over a ring form a ring
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|  |     39 | <LI>Polynomials over an integral domain form an integral domain
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|  |     40 | </MENU>
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|  |     41 | 
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|  |     42 |  <P>Still missing are
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|  |     43 |     Polynomials over a factorial domain form a factorial domain
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|  |     44 |     (difficult), and polynomials over a field form a pid.
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|  |     45 | 
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|  |     46 | <P>[Jacobson1985] Nathan Jacobson, Basic Algebra I, Freeman, 1985.
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|  |     47 | 
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|  |     48 | <P>[Ballarin1999] Clemens Ballarin, Computer Algebra and Theorem Proving,
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|  |     49 |   Author's <A HREF="http://iaks-www.ira.uka.de/iaks-calmet/ballarin/publications.html">PhD thesis</A>, 1999.
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|  |     50 | 
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|  |     51 | <HR>
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|  |     52 | <P>Last modified on $Date$
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|  |     53 | 
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|  |     54 | <ADDRESS>
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|  |     55 | <P><A HREF="http://iaks-www.ira.uka.de/iaks-calmet/ballarin">Clemens Ballarin</A>.  Karlsruhe, October 1999
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|  |     56 | 
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|  |     57 | <A NAME="ballarin@ira.uka.de" HREF="mailto:ballarin@ira.uka.de">ballarin@ira.uka.de</A>
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|  |     58 | </ADDRESS>
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|  |     59 | </BODY></HTML>
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