Eick and Leedham-Green \cite{ELG08} defined for a prime <p> and a fixed
coclass <r> infinite coclass sequences. These sequences consist of finite
<p>-groups of coclass <r>. For each infinite coclass sequence there exists a
consistent pp-presentation (see
Section~"Background on (polycyclic) parametrised presentations")
such that if we choose a natural number for the parameter and possibly reduce
the exponents modulo the relative orders, we obtain a consistent polycyclic
presentation for a group in the sequence; and for each group in the sequence
there exists a natural number such that using this as a value for the
parameter, we obtain a polycyclic presentation for the group.
We use these consistent pp-presentations to compute parametrised
groups, which we call <p>-power-poly-pcp-groups. Furthermore, methods for
these are presented. Without specifying the parameter we compute certain
properties and using the <p>-power-poly-pcp-groups we do this for all groups
they represent at once.
The <p>-power-poly-pcp-groups have a consistent pp-presentation with
generators $g_1, \ldots, g_n, t_1, \ldots t_d$ and $c_1, \ldots, c_m$, for some
non-negative integers <n>, <d> and <m>, and relations of the form, where
$rel[i,j]$ stores the right hand sides of the relations (see
Section~"Background on (polycyclic) parametrised presentations" for more
information on pp-presentations),
%display{nontext}
$$ \eqalign{
&\, g_i^p=rel[i,i],\cr
&\, t_i^{expo} = rel[n+i,n+i],\cr
&\, c_i^{expo\_vec[i]} = rel[n+d+i,n+d+i],\cr
&\, g_i^{g_j} = rel[j,i], \cr
&\, t_i^{g_j} = rel[j,n+i], \cr
&\, t_i^{t_j} = rel[n+j,n+i],
}
$$ %display{text} % g_i^p = rel[i,i], % t_i^{expo} = rel[n+i,n+i], % c_i^{expo\_vec[i]} = rel[n+d+i,n+d+i], % g_i^{g_j} = rel[j,i], % t_i^{g_j} = rel[j,n+i], % t_i^{t_j} = rel[n+j,n+i], %enddisplay
where the $t_i$'s commute modulo $\langle c_1,\ldots, c_m\rangle$ and the
$c_i$'s are central. So (see Section~"Obtaining p-power-poly-pcp-groups")
are the right hand sides of the relations, where some depend on the parameter.
The relative orders <expo> and <expo\_vec[i]> of the generators $t_j$ and
$c_i$ depend on the parameter.
\>PPPPcpGroups( <rel>, <n>, <d>, <m>, <expo>, <expo_vec>, <prime>, <cc>, <name> ) F \>PPPPcpGroups( <rec> ) F
returns the p-power-poly-pcp-groups described by the consistent
pp-presentation with generators $g_1, \ldots, g_n$, $t_1, \ldots t_d$,
$c_1, \ldots, c_m$, for some non-negative integers <n>, <d> and <m>, and
relations of the form
%display{nonhtml} \beginitems
`<rel>' & is the list of the right hand sides of the relations, where each
relation is presented by a list consisting of tuples; the first entry <i> of
a tuple is the index of the generator (if $i \le n$, then it represents
generator $g_i$, if $n \< i \le d$, then it represents generator $t_{i-n}$
and otherwise it represents generator $c_{i-n-d}$) and the second entry of
the tuple is the corresponding exponent.
Note that the exponents of the $g_i$'s are saved as integers and all other
exponents as lists, representing elements depending on the parameter.
`<n>' & is the number of generators $g_i$,
`<d>' & is the number of generators $t_i$,
`<m>' & is the number of generators $c_i$,
`<expo>' & is the relative order of all generators $t_i$; note that is
a list that represents an element depending on the parameter,
`<expo_vec>' & is the list of relative orders, where the th entry of the
list gives the relative order of the generator $c_i$; note that each
relative order is a list that represents an element depending on the
parameter,
`<prime>' & is the underlying prime
,
`<cc>' & if the
-power-poly-pcp-groups represent an infinite coclass
sequence of <p>-groups of coclass <r>, then <cc> = <r>. If they represent
Schur extensions of groups in an infinite coclass sequence, then <cc> is
the coclass of the groups in this infinite coclass sequence.
`<name>' & a string to name the
-power-poly-pcp-groups.
`<rec>' & is a record of the form
<rec( rel, expo, n, d, m, prime, cc, expo_vec, name )>. \enditems %display{nontext} %\beginitems %`<rel>' & is the list of relations, where each relation is presented by a %list consisting of tuples; the first entry <i> of a tuple is the index of the %generator (if $i \le n$, then it represents generator $g_i$, if $n \< i \le d$, %then it represents generator $t_{i-n}$ and otherwise it represents generator %$c_{i-n-d}$) and the second entry of the tuple is the corresponding exponent. %Note that the exponents of the $g_i$'s are saved as integers and all other %exponents as lists, representing elements depending on the parameter. %`<n>' & is the number of generators $g_i$, %`<d>' & is the number of generators $t_i$, %`<m>' & is the number of generators $c_i$, %`<expo>' & is the relative order of all generators $t_i$; note that expo is %given as a list to represent an element depending on the parameter, %`<expo_vec>' & is the list of relative orders, where the <i>th entry of the %list gives the relative order of the generator $c_i$; note that each %relative order is given as a list to represent an element depending on the %parameter, %`<prime>' & is the underlying prime <p>, %`<cc>' & if the <p>-power-poly-pcp-groups represent an infinite coclass %sequence of <p>-groups of coclass <r>, then <cc> = <r>. If they represent %Schur extensions of groups in an infinite coclass sequence, then <cc> is %the coclass of the groups in this infinite coclass sequence. %`<name>' & a string to name the <p>-power-poly-pcp-groups. %`<rec>' & is a record of the form %<rec( rel, expo, n, d, m, prime, cc, expo_vec, name )>. %\enditems %enddisplay
The pp-presentation is described at the beginning of Chapter "p-power-poly-pcp-group". Note that the consistency of the presentation is
checked and that the presentation has to be consistent.
constructs an element in <p>-power-poly-pcp-groups, where <G> is a
<p>-power-poly-pcp-group (thus representing an infinite coclass sequence
through a pp-presentation) with generators $g_1, \ldots, g_n, t_1, \ldots, t_d, c_1, \ldots, c_m$ and <word> is a list of tuples, where the first
entry <i> in the tuple gives the index of the generator (if $i \le n$, then
it represents generator $g_i$, if $n \< i \le d$, then it represents generator
$t_{i-n}$ and otherwise it represents generator $c_{i-n-d}$) and the second
entry of the tuple is the corresponding exponent. Note that the exponents
of the $g_i$'s must be integers, while all other exponents can be integers
or lists, representing an element depending on the parameter.
\beginexample
gap> G := PPPPcpGroups( ParPresGlobalVar_2_1[3] );
< P-Power-Poly-pcp-groups with 3 generators of relative orders [ 2,2,2*2^x ] >
gap> g1 := PPPPcpGroupsElement( G , [[1,1]] );
g1
gap> g := PPPPcpGroupsElement( G , [[1,1],[2,1],[3,1]] );
g1*g2*t1
gap> h := PPPPcpGroupsElement( G , [[1,1],[2,1],[3,G!.expo-1]] );
g1*g2*t1^(-1+2*2^x) \endexample
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \Section{Operations and functions for p-power-poly-pcp-group elements}
The typical operations for group elements can be carried out for
<p>-power-poly-pcp-group elements, like `*', `/', Inverse, One, equality and
ShallowCopy.
\>CollectPPPPcp( <a> ) F
collects the <p>-power-poly-pcp-group element <a> so that after reducing to
integers for every specific value for the parameter <x>, the element is
collected in the polycyclic group, represented by <x> in the underlying
pp-presentation.
Note that the global
variable `COLLECT_PPOWERPOLY_PCP' determines whether every element will be
collected immediately, when created, or not, see %display{tex}
{\tt COLLECT_PPOWERPOLY_PCP}, %enddisplay "COLLECT_PPOWERPOLY_PCP".
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \Section{Operations and functions for p-power-poly-pcp-groups}
For <p>-power-poly-pcp-groups:
\> GeneratorsOfGroup( <G> )
returns a set of generators for the <p>-power-poly-pcp-groups <G>.
\> One( <G> )
obtains the identity element of the <p>-power-poly-pcp-groups <G>.
\>IsConsistentPPPPcp( <G> ) F \>IsConsistentPPPPcp( <ParPres> ) F
checks if the underlying pp-presentation of the
<p>-power-poly-pcp-groups <G> is consistent or if the pp-presenta-tion
<ParPres> is consistent.
\>GetPcGroupPPowerPoly( <ParPres>, <n> ) F \>GetPcGroupPPowerPoly( <G>, <n> ) F
takes the pp-presentation given by the record <ParPres> as in %display{tex}
{\tt PPPPcpGroups}, %enddisplay "PPPPcpGroups" or the <p>-power-poly-pcp-groups <G> and takes <n>, a
non-negative integer, as a value for the parameter to obtain a
pc-presentation for the corresponding finite <p>-group.
\>GetPcpGroupPPowerPoly( <ParPres>, <n> ) F \>GetPcpGroupPPowerPoly( <G>, <n> ) F
takes pp-presentation given by the record <ParPres> as in %display{tex}
{\tt PPPPcpGroups}, %enddisplay "PPPPcpGroups" or the <p>-power-poly-pcp-groups <G> and takes <n>, a
non-negative integer, as the parameter to obtain a pcp-presentation for the
corresponding finite <p>-group, for further information we refer to the
polycyclic package.
\>GAPInputPPPPcpGroups( <file>, <G> ) F \>GAPInputPPPPcpGroups( <file>, <ParPres> ) F
prints the <p>-power-poly-pcp-groups <G> defined by <ParPres> in the file
<file> as a record that could be used as input to %display{tex}
{\tt PPPPcpGroups}, %enddisplay "PPPPcpGroups" to create <p>-power-poly-pcp-groups.
\>GAPInputPPPPcpGroupsAppend( <file>, <G> ) F \>GAPInputPPPPcpGroupsAppend( <file>, <ParPres> ) F
appends the pp-presentation of the <p>-power-poly-pcp-groups <G> defined by
<ParPres> to the file <file> as a record that could be used as input to %display{tex}
{\tt PPPPcpGroups}, %enddisplay "PPPPcpGroups" to create <p>-power-poly-pcp-groups.
\>LatexInputPPPPcpGroups( <file>, <G> ) F \>LatexInputPPPPcpGroups( <file>, <ParPres> ) F
prints the pp-presentation of <G> as given by <ParPres> in latex-code to the
file <file>. Note that only non-trivial relations are printed.
\>LatexInputPPPPcpGroupsAppend( <file>, <G> ) F \>LatexInputPPPPcpGroupsAppend( <file>, <ParPres> ) F
appends the pp-presentation of <G> as given by <ParPres> in latex-code to the
file <file>. Note that only non-trivial relations are appended.
\> LatexInputPPPPcpGroupsAllAppend( <file>, <G> ) F \> LatexInputPPPPcpGroupsAllAppend( <file>, <ParPres> ) F
appends the pp-presentation of <G> as given by <ParPres> in latex-code to the
file <file>. Note that all relations are appended.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \Section{Info classes for the p-power-poly-pcp-groups}
The following info classes are available:
\>`InfoConsistencyPPPPcp' V
is an InfoClass with the following levels.
%display{nonhtml} \beginitems
`level 1' & displays the first consistency relation that fails during the consistency check;
`level 2' & displays which family of consistency relations have been checked during a consistency check. \enditems %display{nontext} %\beginitems %`level 1' & displays the first consistency relation that fails during the consistency check; %`level 2' & displays which family of consistency relations have been checked during a consistency check. %\enditems %enddisplay
the default value is 1.
\>`InfoCollectingPPPPcp' V
is an InfoClass with the following levels.
\beginitems
`level 1' & displays some information during collecting; \enditems
the default value is 0.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \Section{Global variables for the p-power-poly-pcp-groups}
The following global variables are available with default value:
\>`COLLECT_PPOWERPOLY_PCP' V
is a global variable determining if every <p>-power-poly-pcp-group
element is collected, when created, the default value is true.
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