diff options
| author | Juan Marín Noguera <juan@mnpi.eu> | 2025-05-16 22:18:44 +0200 |
|---|---|---|
| committer | Juan Marín Noguera <juan@mnpi.eu> | 2025-05-16 22:18:44 +0200 |
| commit | 4f670b750af5c11e1eac16d9cd8556455f89f46a (patch) | |
| tree | e0f8d7b33df2727d89150f799ee8628821fda80a /2.3.4.1.lyx | |
| parent | 16ccda6c459c0fd7ca2081e9d541124c28b0c556 (diff) | |
Changed layout for more manageable volumes
Diffstat (limited to '2.3.4.1.lyx')
| -rw-r--r-- | 2.3.4.1.lyx | 760 |
1 files changed, 0 insertions, 760 deletions
diff --git a/2.3.4.1.lyx b/2.3.4.1.lyx deleted file mode 100644 index 0eeec27..0000000 --- a/2.3.4.1.lyx +++ /dev/null @@ -1,760 +0,0 @@ -#LyX 2.4 created this file. For more info see https://www.lyx.org/ -\lyxformat 620 -\begin_document -\begin_header -\save_transient_properties true -\origin unavailable -\textclass book -\begin_preamble -\input defs -\end_preamble -\use_default_options true -\maintain_unincluded_children no -\language english -\language_package default -\inputencoding utf8 -\fontencoding auto -\font_roman "default" "default" -\font_sans "default" "default" -\font_typewriter "default" "default" -\font_math "auto" "auto" -\font_default_family default -\use_non_tex_fonts false -\font_sc false -\font_roman_osf false -\font_sans_osf false -\font_typewriter_osf false -\font_sf_scale 100 100 -\font_tt_scale 100 100 -\use_microtype false -\use_dash_ligatures true -\graphics default -\default_output_format default -\output_sync 0 -\bibtex_command default -\index_command default -\float_placement class -\float_alignment class -\paperfontsize default -\spacing single -\use_hyperref false -\papersize default -\use_geometry false -\use_package amsmath 1 -\use_package amssymb 1 -\use_package cancel 1 -\use_package esint 1 -\use_package mathdots 1 -\use_package mathtools 1 -\use_package mhchem 1 -\use_package stackrel 1 -\use_package stmaryrd 1 -\use_package undertilde 1 -\cite_engine basic -\cite_engine_type default -\biblio_style plain -\use_bibtopic false -\use_indices false -\paperorientation portrait -\suppress_date false -\justification true -\use_refstyle 1 -\use_formatted_ref 0 -\use_minted 0 -\use_lineno 0 -\index Index -\shortcut idx -\color #008000 -\end_index -\secnumdepth 3 -\tocdepth 3 -\paragraph_separation indent -\paragraph_indentation default -\is_math_indent 0 -\math_numbering_side default -\quotes_style english -\dynamic_quotes 0 -\papercolumns 1 -\papersides 1 -\paperpagestyle default -\tablestyle default -\tracking_changes false -\output_changes false -\change_bars false -\postpone_fragile_content false -\html_math_output 0 -\html_css_as_file 0 -\html_be_strict false -\docbook_table_output 0 -\docbook_mathml_prefix 1 -\end_header - -\begin_body - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc4[M20] -\end_layout - -\end_inset - -Let -\begin_inset Formula $G'$ -\end_inset - - be a finite free tree in which arrows have been drawn on its edges -\begin_inset Formula $e_{1},\dots,e_{n-1}$ -\end_inset - -; - let -\begin_inset Formula $E_{1},\dots,E_{n-1}$ -\end_inset - - be numbers satisfying Kirchhoff's law (1) in -\begin_inset Formula $G'$ -\end_inset - -. - Show that -\begin_inset Formula $E_{1}=\dots=E_{n-1}=0$ -\end_inset - -. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - -We prove this by induction on -\begin_inset Formula $n$ -\end_inset - -. - For -\begin_inset Formula $n=1$ -\end_inset - - it is trivial. - For -\begin_inset Formula $n>1$ -\end_inset - -, - there always exists a node of degree 1 (in an oriented tree, - this would be a leaf). - Let -\begin_inset Formula $e_{r}$ -\end_inset - - be the only edge connected to that node, - clearly -\begin_inset Formula $E_{r}=0$ -\end_inset - -, - so removing -\begin_inset Formula $e_{r}$ -\end_inset - - leaves us with an isolated node and a free tree of degree 0 which follows Kirchhoff's law and has -\begin_inset Formula $n-1$ -\end_inset - - nodes, - but then by the induction hypothesis all the other -\begin_inset Formula $E_{k}$ -\end_inset - - are also 0. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc8[M25] -\end_layout - -\end_inset - -When applying Kirchhoff's first law to program flow charts, - we usually are interested only in the -\emph on -vertex flows -\emph default - (the number of times each box of the flow chart is performed), - not the edge flows analyzed in the text. - For example, - in the graph of exercise 7, - the vertex flows are -\begin_inset Formula $A=E_{2}+E_{4}$ -\end_inset - -, - -\begin_inset Formula $B=E_{5}$ -\end_inset - -, - -\begin_inset Formula $C=E_{3}+E_{7}+E_{8}$ -\end_inset - -, - -\begin_inset Formula $D=E_{6}+E_{9}$ -\end_inset - -. -\end_layout - -\begin_layout Standard -If we group some vertices together, - treating them as one -\begin_inset Quotes eld -\end_inset - -supervertex, -\begin_inset Quotes erd -\end_inset - - we can combine edge flows that correspond to the same vertex flow. - For example, - edges -\begin_inset Formula $e_{2}$ -\end_inset - - and -\begin_inset Formula $e_{4}$ -\end_inset - - can be combined in the flow chart above if we also put -\begin_inset Formula $B$ -\end_inset - - with -\begin_inset Formula $D$ -\end_inset - -: -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -begin{center} -\end_layout - -\begin_layout Plain Layout - - -\backslash -begin{tikzpicture}[node distance=2cm] -\end_layout - -\begin_layout Plain Layout - - -\backslash -node[circle,draw](Start){Start}; -\end_layout - -\begin_layout Plain Layout - - -\backslash -node[rectangle,draw,right of=Start](A){$A$}; -\end_layout - -\begin_layout Plain Layout - - -\backslash -node[rectangle,draw,right of=A](BD){$B,D$}; -\end_layout - -\begin_layout Plain Layout - - -\backslash -node[rectangle,draw,right of=BD](C){$C$}; -\end_layout - -\begin_layout Plain Layout - - -\backslash -node[circle,draw,right of=C](Stop){Stop}; -\end_layout - -\begin_layout Plain Layout - - -\backslash -draw[->] (Start) -- node[above]{$e_1$} (A); -\end_layout - -\begin_layout Plain Layout - - -\backslash -draw[->] (A) -- node[below]{$e_2+e_4$} (BD); -\end_layout - -\begin_layout Plain Layout - - -\backslash -draw[->,transform canvas={yshift=2pt}] (BD)--node[above]{$e_5$}(C); -\end_layout - -\begin_layout Plain Layout - - -\backslash -draw[->,transform canvas={yshift=-2pt}] (C)--node[below]{$e_7$}(BD); -\end_layout - -\begin_layout Plain Layout - - -\backslash -draw[->] (C) -- node[above]{$e_8$} (Stop); -\end_layout - -\begin_layout Plain Layout - - -\backslash -draw[->] (BD) to[bend right] node[below]{$e_9$} (Stop); -\end_layout - -\begin_layout Plain Layout - - -\backslash -draw[->] (BD) to[loop below] node[left]{$e_6$} (BD); -\end_layout - -\begin_layout Plain Layout - - -\backslash -draw[->] (C) to[bend right] node[above]{$e_3$} (A); -\end_layout - -\begin_layout Plain Layout - - -\backslash -draw[->] (Stop) to[bend right] node[above]{$e_0$} (Start); -\end_layout - -\begin_layout Plain Layout - - -\backslash -end{tikzpicture} -\end_layout - -\begin_layout Plain Layout - - -\backslash -end{center} -\end_layout - -\end_inset - -(Here -\begin_inset Formula $e_{0}$ -\end_inset - - has also been added from Stop to Start, - as in the text.) Continuing this procedure, - we can combine -\begin_inset Formula $e_{3}+e_{7}$ -\end_inset - -, - then -\begin_inset Formula $(e_{3}+e_{7})+e_{8}$ -\end_inset - -, - then -\begin_inset Formula $e_{6}+e_{9}$ -\end_inset - -, - until we obtain the -\emph on -reduced flow chart -\emph default - having edges -\begin_inset Formula $s=e_{1}$ -\end_inset - -, - -\begin_inset Formula $a=e_{2}+e_{4}$ -\end_inset - -, - -\begin_inset Formula $b=e_{5}$ -\end_inset - -, - -\begin_inset Formula $c=e_{3}+e_{7}+e_{8}$ -\end_inset - -, - -\begin_inset Formula $d=e_{6}+e_{9}$ -\end_inset - -, - -\begin_inset Formula $t=e_{0}$ -\end_inset - -, - precisely one edge for each vertex in the original flow chart: -\begin_inset Formula $\text{}$ -\end_inset - - -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -begin{center} -\end_layout - -\begin_layout Plain Layout - - -\backslash -begin{tikzpicture}[node distance=3cm] -\end_layout - -\begin_layout Plain Layout - - -\backslash -node[circle,draw](S){Start}; -\end_layout - -\begin_layout Plain Layout - - -\backslash -node[rectangle,draw,right of=S](M){$A,B,D, -\backslash -text{Stop}$}; -\end_layout - -\begin_layout Plain Layout - - -\backslash -node[rectangle,draw,right of=M](C){$C$}; -\end_layout - -\begin_layout Plain Layout - - -\backslash -draw[->,transform canvas={yshift=2pt}] (S) -- node[above]{$s$} (M); -\end_layout - -\begin_layout Plain Layout - - -\backslash -draw[->,transform canvas={yshift=-2pt}] (M) -- node[below]{$t$} (S); -\end_layout - -\begin_layout Plain Layout - - -\backslash -draw[->,transform canvas={yshift=2pt}] (M) -- node[above]{$b$} (C); -\end_layout - -\begin_layout Plain Layout - - -\backslash -draw[->,transform canvas={yshift=-2pt}] (C) -- node[below]{$c$} (M); -\end_layout - -\begin_layout Plain Layout - - -\backslash -draw[->] (M) to[out=120,in=60,looseness=4] node[left]{$a$ -\backslash - -\backslash - } (M); -\end_layout - -\begin_layout Plain Layout - - -\backslash -draw[->] (M) to[out=300,in=240,looseness=4] node[right]{ -\backslash - $d$} (M); -\end_layout - -\begin_layout Plain Layout - - -\backslash -end{tikzpicture} -\end_layout - -\begin_layout Plain Layout - - -\backslash -end{center} -\end_layout - -\end_inset - - -\end_layout - -\begin_layout Standard -By construction, - Kirchhoff's law holds in this reduced flow chart. - The new edge flows are the vertex flows of the original; - hence the analysis in the text, - applied to the reduced flow chart, - shows how the original vertex flows depend on each other. -\end_layout - -\begin_layout Standard -Prove that this reduction process can be reversed, - in the sense that any set of flows -\begin_inset Formula $\{a,b,\dots\}$ -\end_inset - - satisfying Kirchhoff's law in the reduced flow chart can be -\begin_inset Quotes eld -\end_inset - -split up -\begin_inset Quotes erd -\end_inset - - into a set of edge flows -\begin_inset Formula $\{e_{0},e_{1},\dots\}$ -\end_inset - - in the original flow chart. - These flows -\begin_inset Formula $e_{j}$ -\end_inset - - satisfy Kirchhoff's law and combine to yield the given flows -\begin_inset Formula $\{a,b,\dots\}$ -\end_inset - -; - some of them might, - however, - be negative. - (Although the reduction procedure has been illustrated for only one particular flow chart, - your proof should be valid in general.) -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - - -\begin_inset Note Greyedout -status open - -\begin_layout Plain Layout -(I had to look up the solution, - this one is difficult.) -\end_layout - -\end_inset - - We only have to show that there exists an assignment in the original flowchart that produces any given set of flows in the reduced flowchart. -\end_layout - -\begin_layout Standard -Since we get from one to the other by reductions, - we only have to prove that we can reverse reductions. - In these reductions, - there are two arrows -\begin_inset Formula $e_{1}$ -\end_inset - - from vertex or supervertex -\begin_inset Formula $a$ -\end_inset - - to -\begin_inset Formula $b$ -\end_inset - - and -\begin_inset Formula $e_{2}$ -\end_inset - - from -\begin_inset Formula $a$ -\end_inset - - to -\begin_inset Formula $c$ -\end_inset - -, - to get an edge -\begin_inset Formula $f=e_{1}+e_{2}$ -\end_inset - - from -\begin_inset Formula $a$ -\end_inset - - to -\begin_inset Formula $b,c$ -\end_inset - -, - and reverting means recovering -\begin_inset Formula $e_{1}$ -\end_inset - - and -\begin_inset Formula $e_{2}$ -\end_inset - - from -\begin_inset Formula $f$ -\end_inset - - and the other edges. -\end_layout - -\begin_layout Standard -If -\begin_inset Formula $b=c$ -\end_inset - -, - we can just make up -\begin_inset Formula $e_{1}$ -\end_inset - - and set -\begin_inset Formula $e_{2}$ -\end_inset - - to -\begin_inset Formula $f-e_{1}$ -\end_inset - -. - If -\begin_inset Formula $a=b\neq c$ -\end_inset - -, - then -\begin_inset Formula $e_{2}$ -\end_inset - - must be such that Kirchhoff's law is preserved for -\begin_inset Formula $c$ -\end_inset - -, - and we can just set -\begin_inset Formula $e_{1}=f-e_{2}$ -\end_inset - -. - The situation -\begin_inset Formula $a=c\neq b$ -\end_inset - - is symmetrical. - Finally, - if the three nodes are distinct, - setting -\begin_inset Formula $e_{1}$ -\end_inset - - and -\begin_inset Formula $e_{2}$ -\end_inset - - such that they follow Kirchhoff's law for -\begin_inset Formula $b$ -\end_inset - - and -\begin_inset Formula $c$ -\end_inset - - makes -\begin_inset Formula $e_{1}+e_{2}$ -\end_inset - - follow Kirchhoff's law in -\begin_inset Formula $b,c$ -\end_inset - - in the reduced flowchart. -\end_layout - -\end_body -\end_document |
