src/HOL/Algebra/README.html
author wenzelm
Sun Mar 21 15:57:40 2010 +0100 (2010-03-21)
changeset 35847 19f1f7066917
parent 15582 7219facb3fd0
child 35849 b5522b51cb1e
permissions -rw-r--r--
eliminated old constdefs;
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<H1>Algebra --- Classical Algebra, using Explicit Structures and Locales</H1>
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This directory contains proofs in classical algebra.  It is intended
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as a base for any algebraic development in Isabelle.  Emphasis is on
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reusability.  This is achieved by modelling algebraic structures
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as first-class citizens of the logic (not axiomatic type classes, say).
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The library is expected to grow in future releases of Isabelle.
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Contributions are welcome.
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<H2>GroupTheory, including Sylow's Theorem</H2>
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<P>These proofs are mainly by Florian Kammller.  (Later, Larry
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Paulson simplified some of the proofs.)  These theories were indeed
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the original motivation for locales.
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Here is an outline of the directory's contents: <UL> <LI>Theory <A
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HREF="Group.html"><CODE>Group</CODE></A> defines semigroups, monoids,
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groups, commutative monoids, commutative groups, homomorphisms and the
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subgroup relation.  It also defines the product of two groups
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(This theory was reimplemented by Clemens Ballarin).
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<LI>Theory <A HREF="FiniteProduct.html"><CODE>FiniteProduct</CODE></A> extends
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commutative groups by a product operator for finite sets (provided by
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Clemens Ballarin).
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<LI>Theory <A HREF="Coset.html"><CODE>Coset</CODE></A> defines
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the factorization of a group and shows that the factorization a normal
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subgroup is a group.
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<LI>Theory <A HREF="Bij.html"><CODE>Bij</CODE></A>
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defines bijections over sets and operations on them and shows that they
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are a group.  It shows that automorphisms form a group.
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<LI>Theory <A HREF="Exponent.html"><CODE>Exponent</CODE></A> the
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	    combinatorial argument underlying Sylow's first theorem.
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<LI>Theory <A HREF="Sylow.html"><CODE>Sylow</CODE></A>
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contains a proof of the first Sylow theorem.
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</UL>
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<H2>Rings and Polynomials</H2>
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<UL><LI>Theory <A HREF="CRing.html"><CODE>CRing</CODE></A>
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defines Abelian monoids and groups.  The difference to commutative
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      structures is merely notational:  the binary operation is
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      addition rather than multiplication.  Commutative rings are
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      obtained by inheriting properties from Abelian groups and
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      commutative monoids.  Further structures in the algebraic
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      hierarchy of rings: integral domain.
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<LI>Theory <A HREF="Module.html"><CODE>Module</CODE></A>
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introduces the notion of a R-left-module over an Abelian group, where
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	R is a ring.
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<LI>Theory <A HREF="UnivPoly.html"><CODE>UnivPoly</CODE></A>
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constructs univariate polynomials over rings and integral domains.
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	  Degree function.  Universal Property.
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</UL>
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<H2>Legacy Development of Rings using Axiomatic Type Classes</H2>
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<P>This development of univariate polynomials is separated into an
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abstract development of rings and the development of polynomials
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itself. The formalisation is based on [Jacobson1985], and polynomials
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have a sparse, mathematical representation. These theories were
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developed as a base for the integration of a computer algebra system
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to Isabelle [Ballarin1999], and was designed to match implementations
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of these domains in some typed computer algebra systems.  Summary:
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<P><EM>Rings:</EM>
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  Classes of rings are represented by axiomatic type classes. The
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  following are available:
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<PRE>
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  ring:		Commutative rings with one (including a summation
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		operator, which is needed for the polynomials)
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  domain:	Integral domains
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  factorial:	Factorial domains (divisor chain condition is missing)
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  pid:		Principal ideal domains
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  field:	Fields
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</PRE>
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  Also, some facts about ring homomorphisms and ideals are mechanised.
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<P><EM>Polynomials:</EM>
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  Polynomials have a natural, mathematical representation. Facts about
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  the following topics are provided:
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<MENU>
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<LI>Degree function
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<LI> Universal Property, evaluation homomorphism
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<LI>Long division (existence and uniqueness)
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<LI>Polynomials over a ring form a ring
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<LI>Polynomials over an integral domain form an integral domain
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</MENU>
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<P>[Jacobson1985] Nathan Jacobson, Basic Algebra I, Freeman, 1985.
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<P>[Ballarin1999] Clemens Ballarin, Computer Algebra and Theorem Proving,
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  Author's <A HREF="http://www4.in.tum.de/~ballarin/publications.html">PhD thesis</A>, 1999.
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<HR>
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<P>Last modified on $Date$
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<ADDRESS>
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<P><A HREF="http://www4.in.tum.de/~ballarin">Clemens Ballarin</A>.
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</ADDRESS>
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</BODY>
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</HTML>