- <#1062#>While the techniques discussed here apply in this general setting we are mainly thinking of the case #math54#k = #tex2html_wrap_inline3256#Q,#tex2html_wrap_inline3257# : = #tex2html_wrap_inline3258#C; on
the other side technically we need to (and we can) solve over
#math55##tex2html_wrap_inline3260#Q(V1,…, Vd).<#1062#>
- <#1063#>All over the book I will use the notation
#math59##tex2html_wrap_inline3280#I(F)⊂#tex2html_wrap_inline3281#R in order to denote the ideal generated by the basis
F in the ring #tex2html_wrap_inline3284#R; when there is no ambiguity #tex2html_wrap_inline3286#R will be not specified.<#1063#>
- <#1065#>Recall that
(cf. Definition~<#51#>22.1.2<#51#>) a well-ordering
;SPMlt; on #tex2html_wrap_inline3323#T will be called
a term ordering if it is a <#53#>semigroup ordering<#53#>, <#54#>id est<#54#>
#math67#
t1 ;SPMlt; t2#tex2html_wrap_indisplay3325#tt1 ;SPMlt; tt2,#tex2html_wrap_indisplay3326#t, t1, t2∈#tex2html_wrap_indisplay3327#T.
<#1065#>
- <#1069#>The <#342#>leading polynomial<#342#>
(page~#LePo#343>)
$(g_i)$ is
indicated in <#344#>bold<#344#>.<#1069#>
- <#1070#>Of course, such a statement must be taken <#635#>cum grano salis<#635#>:
it forgets the ill-conditioning problem, which requires at least some suitable
pre-processing before applying the Algorithm.<#1070#>
- <#1071#>Chapter~13 dicusses
both such representations
and the techniques needed in order to solve the required polynomials
#math141#
p(Zi) : = h(a1,…, ai-1, Zi), h∈#tex2html_wrap_indisplay3659#Q[Z1,…, Zi],
where each #math142#ai∈#tex2html_wrap_inline3661#R is given by such
representation.<#1071#>
- <#1072#>Unlike Gröbner's argument which was not intended as an effictive solver and was turn into such by Trinks, Kronecker's argument was an effective solver.
The restriction to the zero-dimensional case is done here to simplify the argument but is <#785#>not<#785#> required by Kronecker's solver which in fact applies also to non-unmixed ideals.
The details on the general case are discussed in Sections~20.3 and 20.4.<#1072#>
- <#1073#>Delassus E.,
<#809#>Sur les systèmes algébriques et leurs relations avec certains
systèmes d'́equations aux dérivées partielles<#809#>. Ann. Éc. Norm.
$3^e$ série <#810#>14<#810#> (1897) 21--44<#1073#>
- <#1074#>Gunther, N.
<#811#>Sur les caractéristiques des systémes d'equations aux dérivées partialles<#811#>,
C.R. Acad. Sci. Paris <#812#>156<#812#> (1913),
1147--1150 and Robinson, L.B.
<#813#>Sur les systémes d'équations aux dérivées partialles<#813#>
C.R. Acad. Sci. Paris <#814#>157<#814#> (1913),
106--108<#1074#>
- <#1075#>Gunther, N.
<#815#>Sur la forme canonique des systèmes d'équations homogènes<#815#> (in russian)
[Journal de l'Institut des Ponts et Chaussées de Russie]
Izdanie Inst. Inz̆. Putej Soobs̆c̆enija Imp. Al. I. <#816#>84<#816#> (1913)
and Gunther, N.
<#817#>Sur la forme canonique des équations algébriques<#817#>, C.R. Acad. Sci. Paris <#818#>157<#818#> (1913),
577--80 .<#1075#>
- <#1077#>the notation $<#826#>J<#826#>_d$ denotes here the set of the homogeneous members of $<#827#>J<#827#>$ of degree $d$ and must not be indentify with the previous notation where $<#828#>J<#828#>_i$ denotes the members of $<#829#>J<#829#>$ depending only on the first $j$ variables.<#1077#>
- <#1079#>We can set $D := {(g) : g&isin#in;G}$
where $G$ is a Gröbner basis of $<#860#>J<#860#>$ wrt $&pr#prec;$ but the existence can be easily derived (as for the finiteness of Gröbner bases) by Hilbert's Nullstellensatz and this is the approach used by Gunther.<#1079#>
- <#1080#>This
is a direct consequence of Corollary~37.2.8 applied to the set $<#871#>T<#871#>_&pr#prec;(f) = <#872#>L<#872#>_;SPMlt;(f)$
and to the
(deg)-lex ordering $&pr#prec;$ induced by $Z_r &pr#prec;...&pr#prec;Z_2 &pr#prec;Z_1$.
Delassus' mistake is to assume that $<#873#>T<#873#>_&pr#prec;(<#874#>J<#874#>_d) = <#875#>L<#875#>_;SPMlt;(<#876#>J<#876#>_d)$ is the set $<#877#>L<#877#>(d)$
consists of the first $#<#878#>L<#878#>_;SPMlt;(<#879#>J<#879#>_d)$ terms w.r.t.
the
(deg)-revlex $;SPMlt;$ induced by $Z_1 ;SPMlt; Z_2 ;SPMlt; ...;SPMlt; Z_r$ which tantamount to the last
$#<#880#>T<#880#>_&pr#prec;(<#881#>J<#881#>_d)$ terms w.r.t.
the
(deg)-lex ordering $&pr#prec;$ induced by $Z_r &pr#prec;...&pr#prec;Z_2 &pr#prec;Z_1$.
In its Lemma (<#882#>cf.<#882#> Section~23.3) Macaulay was considering the same set
$<#883#>L<#883#>(d), #<#884#>L<#884#>(d) = #<#885#>L<#885#>_;SPMlt;(<#886#>J<#886#>_d)$ as Delassus and presented it, as Delassus, in terms of the (deg)-revlex ordering $;SPMlt;$ and not in terms of the
(deg)-lex ordering $&pr#prec;$.
<#1080#>
- <#972#>As a consequence of the elimination property of the lex ordering $&pr#prec;$ which is explicitly stated by Gunther.<#972#>
- <#1024#>Again a consequence of the elimination property of the lex ordering $&pr#prec;$ explicitly stated by Gunther.<#1024#>
- <#1092#>It begins by considering a substitution
#math151#
Z1 = U1, Z2 = AU1 + U2, Z3 = U3,…, Zr = Ur,
where $A$ is a variable,
and the corresponding equations in $K[A][U_1,...,U_r]$ which <#1059#>sont de fonction holomorphes de $A$ dans la voisinage de $A = 0$.<#1059#>
<#1092#>