% \begin{center}
%   \textbf{GNU Free Documentation License}
% \end{center}
% \begin{center}
%   Version 1.3, 3 November 2008
%  
%   Copyright \copyright{} 2000, 2001, 2002, 2007, 2008
%   Free Software Foundation, Inc.
%   
%   \bigskip
%   
%   \url{https://fsf.org/}
%   
%   \bigskip
%   
%   Everyone is permitted to copy and distribute verbatim
%   copies of this license document, but changing it is not
%   allowed.
% \end{center}
% 
% \begin{center}
%   \textbf{\large Preamble}
% \end{center}
% 
% The purpose of this License is to make a manual, textbook,
% or other functional and useful document ``free'' in the
% sense of freedom: to assure everyone the effective freedom
% to copy and redistribute it, with or without modifying it,
% either commercially or noncommercially.  Secondarily, this
% License preserves for the author and publisher a way to get
% credit for their work, while not being considered
% responsible for modifications made by others.
% 
% This License is a kind of ``copyleft'', which means that
% derivative works of the document must themselves be free
% in the same sense. It complements the GNU General Public
% License, which is a copyleft license designed for free
% software.
% 
% We have designed this License in order to use it for
% manuals for free software, because free software needs
% free documentation: a free program should come with
% manuals providing the same freedoms that the software
% does. But this License is not limited to software manuals;
% it can be used for any textual work, regardless of subject
% matter or whether it is published as a printed book. We
% recommend this License principally for works whose purpose
% is instruction or reference.
% 
% \begin{center}
%   \textbf{\Large 1. APPLICABILITY AND DEFINITIONS}
% \end{center}
% 
% This License applies to any manual or other work, in any
% medium, that contains a notice placed by the copyright
% holder saying it can be distributed under the terms of
% this License.  Such a notice grants a world-wide,
% royalty-free license, unlimited in duration, to use that
% work under the conditions stated herein.  The
% ``\textbf{Document}'', below, refers to any such manual or
% work.  Any member of the public is a licensee, and is
% addressed as ``\textbf{you}''. You accept the license if
% you copy, modify or distribute the work in a way requiring
% permission under copyright law.
% 
% A ``\textbf{Modified Version}'' of the Document means any
% work containing the Document or a portion of it, either
% copied verbatim, or with modifications and/or translated
% into another language.
%
% A ``\textbf{Secondary Section}'' is a named appendix or a
% front-matter section of the Document that deals
% exclusively with the relationship of the publishers or
% authors of the Document to the Document's overall subject
% (or to related matters) and contains nothing that could
% fall directly within that overall subject. (Thus, if the
% Document is in part a textbook of mathematics, a Secondary
% Section may not explain any mathematics.)  The
% relationship could be a matter of historical connection
% with the subject or with related matters, or of legal,
% commercial, philosophical, ethical or political position
% regarding them.
%
% The ``\textbf{Invariant Sections}'' are certain Secondary
% Sections whose titles are designated, as being those of
% Invariant Sections, in the notice that says that the
% Document is released under this License. If a section does
% not fit the above definition of Secondary then it is not
% allowed to be designated as Invariant.  The Document may
% contain zero Invariant Sections.  If the Document does not
% identify any Invariant Sections then there are none.
%
% The ``\textbf{Cover Texts}'' are certain short passages of
% text that are listed, as Front-Cover Texts or Back-Cover
% Texts, in the notice that says that the Document is
% released under this License. A Front-Cover Text may be at
% most 5 words, and a Back-Cover Text may be at most 25
% words.
%
% A ``\textbf{Transparent}'' copy of the Document means a
% machine-readable copy, represented in a format whose
% specification is available to the general public, that is
% suitable for revising the document straightforwardly with
% generic text editors or (for images composed of pixels)
% generic paint programs or (for drawings) some widely
% available drawing editor, and that is suitable for input
% to text formatters or for automatic translation to a
% variety of formats suitable for input to text formatters.
% A copy made in an otherwise Transparent file format whose
% markup, or absence of markup, has been arranged to thwart
% or discourage subsequent modification by readers is not
% Transparent. An image format is not Transparent if used
% for any substantial amount of text.  A copy that is not
% ``Transparent'' is called ``\textbf{Opaque}''.
%
% Examples of suitable formats for Transparent copies
% include plain ASCII without markup, Texinfo input format,
% LaTeX input format, SGML or XML using a publicly available
% DTD, and standard-conforming simple HTML, PostScript or
% PDF designed for human modification. Examples of
% transparent image formats include PNG, XCF and JPG.
% Opaque formats include proprietary formats that can be
% read and edited only by proprietary word processors, SGML
% or XML for which the DTD and/or processing tools are not
% generally available, and the machine-generated HTML,
% PostScript or PDF produced by some word processors for
% output purposes only.
%
% The ``\textbf{Title Page}'' means, for a printed book, the
% title page itself, plus such following pages as are needed
% to hold, legibly, the material this License requires to
% appear in the title page. For works in formats which do
% not have any title page as such, ``Title Page'' means the
% text near the most prominent appearance of the work's
% title, preceding the beginning of the body of the text.
%
% The ``\textbf{publisher}'' means any person or entity that
% distributes copies of the Document to the public.
%
% A section ``\textbf{Entitled XYZ}'' means a named subunit
% of the Document whose title either is precisely XYZ or
% contains XYZ in parentheses following text that translates
% XYZ in another language.  (Here XYZ stands for a specific
% section name mentioned below, such as
% ``\textbf{Acknowledgements}'', ``\textbf{Dedications}'',
% ``\textbf{Endorsements}'', or ``\textbf{History}''.) To
% ``\textbf{Preserve the Title}'' of such a section when you
% modify the Document means that it remains a section
% ``Entitled XYZ'' according to this definition.
%
% The Document may include Warranty Disclaimers next to the
% notice which states that this License applies to the
% Document. These Warranty Disclaimers are considered to be
% included by reference in this License, but only as regards
% disclaiming warranties: any other implication that these
% Warranty Disclaimers may have is void and has no effect on
% the meaning of this License.
%
% \begin{center}
%   \textbf{\Large 2. VERBATIM COPYING}
% \end{center}
%
% You may copy and distribute the Document in any medium,
% either commercially or noncommercially, provided that this
% License, the copyright notices, and the license notice
% saying this License applies to the Document are reproduced
% in all copies, and that you add no other conditions
% whatsoever to those of this License. You may not use
% technical measures to obstruct or control the reading or
% further copying of the copies you make or distribute.
% However, you may accept compensation in exchange for
% copies. If you distribute a large enough number of copies
% you must also follow the conditions in section~3.
%
% You may also lend copies, under the same conditions stated
% above, and you may publicly display copies.
%
% \begin{center}
%   \textbf{\Large 3. COPYING IN QUANTITY}
% \end{center}
%
% If you publish printed copies (or copies in media that
% commonly have printed covers) of the Document, numbering
% more than 100, and the Document's license notice requires
% Cover Texts, you must enclose the copies in covers that
% carry, clearly and legibly, all these Cover Texts:
% Front-Cover Texts on the front cover, and Back-Cover Texts
% on the back cover.  Both covers must also clearly and
% legibly identify you as the publisher of these copies.
% The front cover must present the full title with all words
% of the title equally prominent and visible.  You may add
% other material on the covers in addition. Copying with
% changes limited to the covers, as long as they preserve
% the title of the Document and satisfy these conditions,
% can be treated as verbatim copying in other respects.
% 
% If the required texts for either cover are too voluminous
% to fit legibly, you should put the first ones listed (as
% many as fit reasonably) on the actual cover, and continue
% the rest onto adjacent pages.
%
% If you publish or distribute Opaque copies of the Document
% numbering more than 100, you must either include a
% machine-readable Transparent copy along with each Opaque
% copy, or state in or with each Opaque copy a
% computer-network location from which the general
% network-using public has access to download using
% public-standard network protocols a complete Transparent
% copy of the Document, free of added material. If you use
% the latter option, you must take reasonably prudent steps,
% when you begin distribution of Opaque copies in quantity,
% to ensure that this Transparent copy will remain thus
% accessible at the stated location until at least one year
% after the last time you distribute an Opaque copy
% (directly or through your agents or retailers) of that
% edition to the public.
%
% It is requested, but not required, that you contact the
% authors of the Document well before redistributing any
% large number of copies, to give them a chance to provide
% you with an updated version of the Document.
%
% \begin{center}
%   \textbf{\Large 4. MODIFICATIONS}
% \end{center}
%
% You may copy and distribute a Modified Version of the
% Document under the conditions of sections 2 and 3 above,
% provided that you release the Modified Version under
% precisely this License, with the Modified Version filling
% the role of the Document, thus licensing distribution and
% modification of the Modified Version to whoever possesses
% a copy of it.  In addition, you must do these things in
% the Modified Version:
%
% \begin{itemize}
% \item[A.] 
%   Use in the Title Page (and on the covers, if any) a
%   title distinct from that of the Document, and from those
%   of previous versions (which should, if there were any,
%   be listed in the History section of the Document). You
%   may use the same title as a previous version if the
%   original publisher of that version gives permission.
%   
% \item[B.]
%   List on the Title Page, as authors, one or more persons
%   or entities responsible for authorship of the
%   modifications in the Modified Version, together with at
%   least five of the principal authors of the Document (all
%   of its principal authors, if it has fewer than five),
%   unless they release you from this requirement.
%   
% \item[C.]
%   State on the Title page the name of the publisher of the
%   Modified Version, as the publisher.
%
% \item[D.]
%   Preserve all the copyright notices of the Document.
%   
% \item[E.]
%   Add an appropriate copyright notice for your
%   modifications adjacent to the other copyright notices.
%  
% \item[F.]
%   Include, immediately after the copyright notices, a
%   license notice giving the public permission to use the
%   Modified Version under the terms of this License, in the
%   form shown in the Addendum below.
%  
% \item[G.]
%   Preserve in that license notice the full lists of
%   Invariant Sections and required Cover Texts given in the
%   Document's license notice.
% 
% \item[H.]
%   Include an unaltered copy of this License.
% 
% \item[I.]
%   Preserve the section Entitled ``History'', Preserve its
%   Title, and add to it an item stating at least the title,
%   year, new authors, and publisher of the Modified Version
%   as given on the Title Page. If there is no section
%   Entitled ``History'' in the Document, create one stating
%   the title, year, authors, and publisher of the Document
%   as given on its Title Page, then add an item describing
%   the Modified Version as stated in the previous
%   sentence.
%  
% \item[J.]
%   Preserve the network location, if any, given in the
%   Document for public access to a Transparent copy of the
%   Document, and likewise the network locations given in
%   the Document for previous versions it was based on.
%   These may be placed in the ``History'' section. You may
%   omit a network location for a work that was published at
%   least four years before the Document itself, or if the
%   original publisher of the version it refers to gives
%   permission.
%  
% \item[K.]
%   For any section Entitled ``Acknowledgements'' or
%   ``Dedications'', Preserve the Title of the section, and
%   preserve in the section all the substance and tone of
%   each of the contributor acknowledgements and/or
%   dedications given therein.
%  
% \item[L.]
%   Preserve all the Invariant Sections of the Document,
%   unaltered in their text and in their titles. Section
%   numbers or the equivalent are not considered part of the
%   section titles.
%  
% \item[M.]
%   Delete any section Entitled ``Endorsements''. Such a
%   section may not be included in the Modified Version.
%  
% \item[N.]
%   Do not retitle any existing section to be Entitled
%   ``Endorsements'' or to conflict in title with any
%   Invariant Section.
%  
% \item[O.]
%   Preserve any Warranty Disclaimers.
% \end{itemize}
%
% If the Modified Version includes new front-matter sections
% or appendices that qualify as Secondary Sections and
% contain no material copied from the Document, you may at
% your option designate some or all of these sections as
% invariant. To do this, add their titles to the list of
% Invariant Sections in the Modified Version's license
% notice. These titles must be distinct from any other
% section titles.
%
% You may add a section Entitled ``Endorsements'', provided
% it contains nothing but endorsements of your Modified
% Version by various parties---for example, statements of
% peer review or that the text has been approved by an
% organization as the authoritative definition of a
% standard.
%
% You may add a passage of up to five words as a Front-Cover
% Text, and a passage of up to 25 words as a Back-Cover
% Text, to the end of the list of Cover Texts in the
% Modified Version.  Only one passage of Front-Cover Text
% and one of Back-Cover Text may be added by (or through
% arrangements made by) any one entity. If the Document
% already includes a cover text for the same cover,
% previously added by you or by arrangement made by the same
% entity you are acting on behalf of, you may not add
% another; but you may replace the old one, on explicit
% permission from the previous publisher that added the old
% one.
%
% The author(s) and publisher(s) of the Document do not by
% this License give permission to use their names for
% publicity for or to assert or imply endorsement of any
% Modified Version.
%
% \begin{center}
%   \textbf{\Large 5. COMBINING DOCUMENTS}
% \end{center}
%
% You may combine the Document with other documents released
% under this License, under the terms defined in section~4
% above for modified versions, provided that you include in
% the combination all of the Invariant Sections of all of
% the original documents, unmodified, and list them all as
% Invariant Sections of your combined work in its license
% notice, and that you preserve all their Warranty
% Disclaimers.
%
% The combined work need only contain one copy of this
% License, and multiple identical Invariant Sections may be
% replaced with a single copy. If there are multiple
% Invariant Sections with the same name but different
% contents, make the title of each such section unique by
% adding at the end of it, in parentheses, the name of the
% original author or publisher of that section if known, or
% else a unique number. Make the same adjustment to the
% section titles in the list of Invariant Sections in the
% license notice of the combined work.
%
% In the combination, you must combine any sections Entitled
% ``History'' in the various original documents, forming one
% section Entitled ``History''; likewise combine any
% sections Entitled ``Acknowledgements'', and any sections
% Entitled ``Dedications''. You must delete all sections
% Entitled ``Endorsements''.
%
% \begin{center}
%   \textbf{\Large 6. COLLECTIONS OF DOCUMENTS}
% \end{center}
%
% You may make a collection consisting of the Document and
% other documents released under this License, and replace
% the individual copies of this License in the various
% documents with a single copy that is included in the
% collection, provided that you follow the rules of this
% License for verbatim copying of each of the documents in
% all other respects.
%
% You may extract a single document from such a collection,
% and distribute it individually under this License,
% provided you insert a copy of this License into the
% extracted document, and follow this License in all other
% respects regarding verbatim copying of that document.
%
% \begin{center}
%   \textbf{\Large 7. AGGREGATION WITH INDEPENDENT WORKS}
% \end{center}
%
% A compilation of the Document or its derivatives with
% other separate and independent documents or works, in or
% on a volume of a storage or distribution medium, is called
% an ``aggregate'' if the copyright resulting from the
% compilation is not used to limit the legal rights of the
% compilation's users beyond what the individual works
% permit. When the Document is included in an aggregate,
% this License does not apply to the other works in the
% aggregate which are not themselves derivative works of the
% Document.
%
% If the Cover Text requirement of section~3 is applicable
% to these copies of the Document, then if the Document is
% less than one half of the entire aggregate, the Document's
% Cover Texts may be placed on covers that bracket the
% Document within the aggregate, or the electronic
% equivalent of covers if the Document is in electronic
% form. Otherwise they must appear on printed covers that
% bracket the whole aggregate.
%
% \begin{center}
%   \textbf{\Large 8. TRANSLATION}
% \end{center}
%
% Translation is considered a kind of modification, so you
% may distribute translations of the Document under the
% terms of section~4. Replacing Invariant Sections with
% translations requires special permission from their
% copyright holders, but you may include translations of
% some or all Invariant Sections in addition to the original
% versions of these Invariant Sections. You may include a
% translation of this License, and all the license notices
% in the Document, and any Warranty Disclaimers, provided
% that you also include the original English version of this
% License and the original versions of those notices and
% disclaimers. In case of a disagreement between the
% translation and the original version of this License or a
% notice or disclaimer, the original version will prevail.
%
% If a section in the Document is Entitled
% ``Acknowledgements'', ``Dedications'', or ``History'', the
% requirement (section~4) to Preserve its Title (section~1)
% will typically require changing the actual title.
%
% \begin{center}
%   \textbf{\Large 9. TERMINATION}
% \end{center}
%
% You may not copy, modify, sublicense, or distribute the
% Document except as expressly provided under this
% License. Any attempt otherwise to copy, modify,
% sublicense, or distribute it is void, and will
% automatically terminate your rights under this License.
%
% However, if you cease all violation of this License, then
% your license from a particular copyright holder is
% reinstated (a) provisionally, unless and until the
% copyright holder explicitly and finally terminates your
% license, and (b) permanently, if the copyright holder
% fails to notify you of the violation by some reasonable
% means prior to 60 days after the cessation.
%
% Moreover, your license from a particular copyright holder
% is reinstated permanently if the copyright holder notifies
% you of the violation by some reasonable means, this is the
% first time you have received notice of violation of this
% License (for any work) from that copyright holder, and you
% cure the violation prior to 30 days after your receipt of
% the notice.
%
% Termination of your rights under this section does not
% terminate the licenses of parties who have received copies
% or rights from you under this License.  If your rights
% have been terminated and not permanently reinstated,
% receipt of a copy of some or all of the same material does
% not give you any rights to use it.
%
% \begin{center}
%   \textbf{\Large 10. FUTURE REVISIONS OF THIS LICENSE}
% \end{center}
%
% The Free Software Foundation may publish new, revised
% versions of the GNU Free Documentation License from time
% to time. Such new versions will be similar in spirit to
% the present version, but may differ in detail to address
% new problems or concerns. See
% \texttt{https://www.gnu.org/licenses/}.
%
% Each version of the License is given a distinguishing
% version number. If the Document specifies that a
% particular numbered version of this License ``or any later
% version'' applies to it, you have the option of following
% the terms and conditions either of that specified version
% or of any later version that has been published (not as a
% draft) by the Free Software Foundation. If the Document
% does not specify a version number of this License, you may
% choose any version ever published (not as a draft) by the
% Free Software Foundation. If the Document specifies that a
% proxy can decide which future versions of this License can
% be used, that proxy's public statement of acceptance of a
% version permanently authorizes you to choose that version
% for the Document.
%
% \begin{center}
%   \textbf{\Large 11. RELICENSING}
% \end{center}
%
% ``Massive Multiauthor Collaboration Site'' (or ``MMC
% Site'') means any World Wide Web server that publishes
% copyrightable works and also provides prominent facilities
% for anybody to edit those works. A public wiki that
% anybody can edit is an example of such a server. A
% ``Massive Multiauthor Collaboration'' (or ``MMC'')
% contained in the site means any set of copyrightable works
% thus published on the MMC site.
%
% ``CC-BY-SA'' means the Creative Commons Attribution-Share
% Alike 3.0 license published by Creative Commons
% Corporation, a not-for-profit corporation with a principal
% place of business in San Francisco, California, as well as
% future copyleft versions of that license published by that
% same organization.
%
% ``Incorporate'' means to publish or republish a Document,
% in whole or in part, as part of another Document.
%
% An MMC is ``eligible for relicensing'' if it is licensed
% under this License, and if all works that were first
% published under this License somewhere other than this
% MMC, and subsequently incorporated in whole or in part
% into the MMC, (1) had no cover texts or invariant
% sections, and (2) were thus incorporated prior to November
% 1, 2008.
%
% The operator of an MMC Site may republish an MMC contained
% in the site under CC-BY-SA on the same site at any time
% before August 1, 2009, provided the MMC is eligible for
% relicensing.
%
% \begin{center}
%   \textbf{\Large ADDENDUM: How to use this License for
%   your documents}
% \end{center}
%
% To use this License in a document you have written,
% include a copy of the License in the document and put the
% following copyright and license notices just after the
% title page:
%
% \bigskip
% \begin{quote}
%   Copyright \copyright{}  YEAR  YOUR NAME.
%   Permission is granted to copy, distribute and/or modify
%   this document under the terms of the GNU Free
%   Documentation License, Version 1.3 or any later version
%   published by the Free Software Foundation; with no
%   Invariant Sections, no Front-Cover Texts, and no
%   Back-Cover Texts. A copy of the license is included in
%   the section entitled ``GNU Free Documentation
%   License''.
% \end{quote}
% \bigskip
%
% If you have Invariant Sections, Front-Cover Texts and
% Back-Cover Texts, replace the ``with \dots\ Texts.''\ line
% with this:
%
% \bigskip
% \begin{quote}
%   with the Invariant Sections being LIST THEIR TITLES,
%   with the Front-Cover Texts being LIST, and with the
%   Back-Cover Texts being LIST.
% \end{quote}
% \bigskip
%
% If you have Invariant Sections without Cover Texts, or
% some other combination of the three, merge those two
% alternatives to suit the situation.
%
% If your document contains nontrivial examples of program
% code, we recommend releasing these examples in parallel
% under your choice of free software license, such as the
% GNU General Public License, to permit their use in free
% software.