#LyX 2.3 created this file. For more info see http://www.lyx.org/ \lyxformat 544 \begin_document \begin_header \save_transient_properties true \origin unavailable \textclass article \begin_preamble \usepackage{siunitx} \usepackage{pgfplots} \usepackage{listings} \usepackage{multicol} \sisetup{output-decimal-marker = {,}, quotient-mode=fraction, output-exponent-marker=\ensuremath{\mathrm{3}}} \DeclareMathOperator{\g}{g} \DeclareMathOperator{\sled}{sled} \DeclareMathOperator{\Aut}{Aut} \DeclareMathOperator{\Cir}{Cir} \DeclareMathOperator{\ecc}{ecc} \DeclareMathOperator{\rad}{rad} \DeclareMathOperator{\diam}{diam} \newcommand\euler{e} \end_preamble \use_default_options true \begin_modules enumitem \end_modules \maintain_unincluded_children false \language slovene \language_package default \inputencoding auto \fontencoding global \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_osf false \font_sf_scale 100 100 \font_tt_scale 100 100 \use_microtype false \use_dash_ligatures true \graphics xetex \default_output_format default \output_sync 0 \bibtex_command default \index_command default \paperfontsize default \spacing single \use_hyperref false \papersize default \use_geometry true \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 false \use_refstyle 1 \use_minted 0 \index Index \shortcut idx \color #008000 \end_index \leftmargin 1cm \topmargin 1cm \rightmargin 1cm \bottommargin 2cm \headheight 1cm \headsep 1cm \footskip 1cm \secnumdepth 3 \tocdepth 3 \paragraph_separation indent \paragraph_indentation default \is_math_indent 0 \math_numbering_side default \quotes_style german \dynamic_quotes 0 \papercolumns 1 \papersides 1 \paperpagestyle default \tracking_changes false \output_changes false \html_math_output 0 \html_css_as_file 0 \html_be_strict false \end_header \begin_body \begin_layout Standard \begin_inset ERT status open \begin_layout Plain Layout \backslash setlength{ \backslash columnseprule}{0.2pt} \backslash begin{multicols}{2} \end_layout \end_inset \end_layout \begin_layout Standard Največja stopnja \begin_inset Formula $\Delta G$ \end_inset , najmanjša \begin_inset Formula $\delta G$ \end_inset . \end_layout \begin_layout Standard Rokovanje: \begin_inset Formula $\sum_{v\in VG}\deg_{G}v=2\left|EG\right|$ \end_inset . \end_layout \begin_layout Standard Vsak graf ima sodo mnogo vozlišč lihe stopnje. \end_layout \begin_layout Standard Presek/unija grafov je presek/unija njunih \begin_inset Formula $V$ \end_inset in \begin_inset Formula $E$ \end_inset . \end_layout \begin_layout Standard \begin_inset Formula $G\cup H$ \end_inset je disjunktna unija grafov \begin_inset Formula $\sim$ \end_inset \begin_inset Formula $VG\cap VH=\emptyset$ \end_inset . \end_layout \begin_layout Standard Komplement grafa: \begin_inset Formula $\overline{G}$ \end_inset (obratna povezanost) \end_layout \begin_layout Standard \begin_inset Formula $0\leq\left|EG\right|\leq{\left|VG\right| \choose 2}\quad\quad\quad$ \end_inset Za padajoče \begin_inset Formula $d_{i}$ \end_inset velja: \end_layout \begin_layout Standard \begin_inset Formula $\left(d_{1},\dots d_{n}\right)$ \end_inset graf \begin_inset Formula $\Leftrightarrow\left(d_{2}-1,\dots,d_{d_{1}+1}-1,\dots,d_{n}\right)$ \end_inset graf \end_layout \begin_layout Standard Če je \begin_inset Formula $AG$ \end_inset matrika sosednosti, \begin_inset Formula $\left(\left(AG\right)^{n}\right)_{i,j}$ \end_inset pove št. \begin_inset Formula $i,j-$ \end_inset poti. \end_layout \begin_layout Standard \begin_inset Formula \[ \text{Število trikotnikov: }\frac{\sled\left(\left(AG\right)^{3}\right)}{2\cdot3} \] \end_inset \end_layout \begin_layout Standard \begin_inset Formula $\left|EK_{n}\right|={n \choose 2}$ \end_inset , \begin_inset Formula ${n \choose k}=\frac{n!}{k!\left(n-k\right)!}$ \end_inset \end_layout \begin_layout Paragraph Sprehod \end_layout \begin_layout Standard je zaporedje vozlišč, ki so verižno povezana. \end_layout \begin_layout Standard Dolžina sprehoda je število prehojenih povezav. \end_layout \begin_layout Standard Sklenjen sprehod dolžine \begin_inset Formula $k$ \end_inset : \begin_inset Formula $v_{0}=v_{k}$ \end_inset \end_layout \begin_layout Standard Enostaven sprehod ima disjunktna vozlišča razen \begin_inset Formula $\left(v_{0},v_{k}\right)$ \end_inset . \end_layout \begin_layout Standard Pot v grafu: podgraf \begin_inset Formula $P_{k}$ \end_inset \begin_inset Formula $\sim$ \end_inset enostaven nesklenjen sprehod. \end_layout \begin_layout Paragraph Cikel \end_layout \begin_layout Standard podgraf, ki je enostaven sklenjen sprehod dolžine \begin_inset Formula $>3$ \end_inset . \end_layout \begin_layout Standard Če v \begin_inset Formula $G$ \end_inset \begin_inset Formula $\exists$ \end_inset dve različni \begin_inset Formula $u,v-$ \end_inset poti \begin_inset Formula $\Leftrightarrow$ \end_inset \begin_inset Formula $G$ \end_inset premore cikel \end_layout \begin_layout Standard Sklenjen sprehod lihe dolžine \begin_inset Formula $\in G$ \end_inset \begin_inset Formula $\Leftrightarrow$ \end_inset lih cikel \begin_inset Formula $\in G$ \end_inset \end_layout \begin_layout Paragraph Povezanost \end_layout \begin_layout Standard \begin_inset Formula $u,v$ \end_inset sta v isti komponenti \begin_inset Formula $\text{\ensuremath{\sim}}$ \end_inset \begin_inset Formula $\text{\ensuremath{\exists}}$ \end_inset \begin_inset Formula $u,v-$ \end_inset pot \end_layout \begin_layout Standard Število komponent grafa: \begin_inset Formula $\Omega G$ \end_inset . \begin_inset Formula $G$ \end_inset povezan \begin_inset Formula $\sim\Omega G=1$ \end_inset \end_layout \begin_layout Standard Komponenta je maksimalen povezan podgraf. \end_layout \begin_layout Standard Premer: \begin_inset Formula $\diam G=\max\left\{ d_{G}\left(v,u\right);\forall v,u\in VG\right\} $ \end_inset \end_layout \begin_layout Standard Ekscentričnost: \begin_inset Formula $\ecc_{G}u=max\left\{ d_{G}\left(u,x\right);\forall x\in VG\right\} $ \end_inset \end_layout \begin_layout Standard Polmer: \begin_inset Formula $\rad G=\min\left\{ \ecc u;\forall u\in VG\right\} $ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $\diam C_{n}=\rad C_{n}=\lfloor\frac{n}{2}\rfloor$ \end_inset \end_layout \begin_layout Standard (Liha) ožina ( \begin_inset Formula $\g G$ \end_inset ) je dolžina najkrajšega (lihega) cikla. \end_layout \begin_layout Standard Vsaj en od \begin_inset Formula $G$ \end_inset in \begin_inset Formula $\overline{G}$ \end_inset je povezan. \end_layout \begin_layout Standard Povezava \begin_inset Formula $e$ \end_inset je most \begin_inset Formula $\Leftrightarrow$ \end_inset \begin_inset Formula $\Omega\left(G-e\right)>\Omega G$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $u$ \end_inset je prerezno vozlišče \begin_inset Formula $\Leftrightarrow$ \end_inset \begin_inset Formula $\Omega\left(G-u\right)>\Omega G$ \end_inset \end_layout \begin_layout Standard Za nepovezan \begin_inset Formula $G$ \end_inset velja \begin_inset Formula $\diam\overline{G}\leq2$ \end_inset \end_layout \begin_layout Paragraph Dvodelni \end_layout \begin_layout Standard \begin_inset Formula $\sim V=A\cup B,A\cap B=\emptyset,\forall uv\in E:u\in A\oplus v\in A$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $K_{m,n}$ \end_inset je poln dvodelni graf, \begin_inset Formula $\left|A\right|=m$ \end_inset , \begin_inset Formula $\left|B\right|=n$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $G$ \end_inset dvodelen \begin_inset Formula $\Leftrightarrow\forall$ \end_inset komponenta \begin_inset Formula $G$ \end_inset dvodelna \end_layout \begin_layout Standard Pot, sod cikel, hiperkocka so dvodelni, petersenov ni. \end_layout \begin_layout Standard \begin_inset Formula $G$ \end_inset dvodelen \begin_inset Formula $\Leftrightarrow G$ \end_inset ne vsebuje lihega cikla. \end_layout \begin_layout Standard Biparticija glede na parnost \begin_inset Formula $d_{G}\left(u,x_{0}\right)$ \end_inset , \begin_inset Formula $x_{0}$ \end_inset fiksen. \end_layout \begin_layout Standard Dvodelen \begin_inset Formula $k-$ \end_inset regularen, \begin_inset Formula $\left|E\right|\ge1\Rightarrow$ \end_inset \begin_inset Formula $\left|A\right|=\left|B\right|$ \end_inset . Dokaz: \begin_inset Formula $\sum_{u\in A}\deg u=\left|E\right|=\cancel{k}\left|A\right|=\cancel{k}\left|B\right|=\sum_{u\in B}\deg u$ \end_inset \end_layout \begin_layout Paragraph Krožni \end_layout \begin_layout Standard \begin_inset Formula $\Cir\left(n,\left\{ s_{1},\dots,s_{k}\right\} \right):\left|V\right|=n,$ \end_inset množica preskokov \end_layout \begin_layout Standard \begin_inset Formula $\Omega\Cir\left(n,\left\{ s,n-s\right\} \right)=\gcd\left\{ n,s\right\} $ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $W_{n}$ \end_inset (kolo) pa je cikel z univerzalnim vozliščem. \end_layout \begin_layout Paragraph Homomorfizem \end_layout \begin_layout Standard \begin_inset Formula $\varphi:VG\to VH$ \end_inset slika povezave v povezave \end_layout \begin_layout Standard Primer: \begin_inset Formula $K_{2}$ \end_inset je homomorfna slika \begin_inset Formula $\forall$ \end_inset bipartitnega grafa. \end_layout \begin_layout Standard V povezavah in vozliščih surjektiven \begin_inset Formula $hm\varphi$ \end_inset je epimorfizem. \end_layout \begin_layout Standard V vozliščih injektiven \begin_inset Formula $hm\varphi$ \end_inset je monomorfizem/vložitev. \end_layout \begin_layout Standard Vložitev, ki ohranja razdalje, je izometrična. \end_layout \begin_layout Standard Kompozitum homomorfizmov je spet homomorfizem. \end_layout \begin_layout Standard Izomorfizem je bijektivni \begin_inset Formula $hm\varphi$ \end_inset s homomorfnim inverzom. \end_layout \begin_layout Standard \begin_inset Formula $im\varphi$ \end_inset \begin_inset Formula $f:VG\to VH$ \end_inset \begin_inset Formula $\forall u,v\in VG:uv\in EG\Leftrightarrow fufv\in EH$ \end_inset \end_layout \begin_layout Standard Nad množico vseh grafov \begin_inset Formula $\mathcal{G}$ \end_inset je izomorfizem ( \begin_inset Formula $\cong$ \end_inset ) ekv. rel. \end_layout \begin_layout Standard \begin_inset Formula $im\varphi$ \end_inset \begin_inset Formula $G\to G$ \end_inset je avtomorfizem. \end_layout \begin_layout Standard \begin_inset Formula $\Aut G$ \end_inset je grupa avtomorfizmov s komponiranjem. \end_layout \begin_layout Standard \begin_inset Formula $\Aut K_{n}=\left\{ \pi\in S_{n}=\text{permutacije }n\text{ elementov}\right\} $ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $\Aut P_{n}=\left\{ \text{trivialni }id,f\left(i\right)=n-i-1\right\} $ \end_inset , \begin_inset Formula $\Aut G\cong\Aut\overline{G}$ \end_inset \end_layout \begin_layout Standard Izomorfizem ohranja stopnje, št. \begin_inset Formula $C_{4}$ \end_inset , povezanost, \begin_inset Formula $\left|EG\right|,\dots$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $G\cong\overline{G}\Rightarrow\left|VG\right|\%4\in\left\{ 0,1\right\} $ \end_inset \end_layout \begin_layout Paragraph Operacije \end_layout \begin_layout Standard \begin_inset Formula $H$ \end_inset vpeti podgraf \begin_inset Formula $G\Leftrightarrow\exists F\subseteq EG\ni:H=G-F$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $H$ \end_inset inducirani podgraf \begin_inset Formula $G\Leftrightarrow\exists S\subseteq VG\ni:H=G-S$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $H$ \end_inset podgraf \begin_inset Formula $G\Leftrightarrow\exists S\subseteq VG,F\subseteq EG\ni:H=\left(G-F\right)-S$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $uv=e\in EG$ \end_inset . \begin_inset Formula $G/e$ \end_inset je skrčitev. (identificiramo \begin_inset Formula $u=v$ \end_inset ) \end_layout \begin_layout Standard \begin_inset Formula $H$ \end_inset minor \begin_inset Formula $G$ \end_inset : \begin_inset Formula $H=f_{1}...f_{k}G$ \end_inset za \begin_inset Formula $f_{i}$ \end_inset skrčitev/odstranjevanje \end_layout \begin_layout Standard \begin_inset Formula $VG^{+}e\coloneqq VG\cup\left\{ x_{e}\right\} $ \end_inset , \begin_inset Formula $EG^{+}e\coloneqq EG\setminus e\cup\left\{ x_{e}u,x_{e}v\right\} $ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $VG^{+}e$ \end_inset je subdivizija, \begin_inset Formula $e\in EG$ \end_inset . Na \begin_inset Formula $e$ \end_inset dodamo vozlišče. \end_layout \begin_layout Standard \begin_inset Formula $H$ \end_inset subdivizija \begin_inset Formula $G$ \end_inset \begin_inset Formula $\Leftrightarrow H=G^{+}\left\{ e_{1},\dots,e_{k}\right\} ^{+}\left\{ f_{1}\dots f_{j}\right\} ^{+}\dots$ \end_inset \end_layout \begin_layout Standard Stopnja vozlišč se s subdivizijo ne poveča. \end_layout \begin_layout Standard Glajenje \begin_inset Formula $G^{-}v$ \end_inset , \begin_inset Formula $v\in VG$ \end_inset je obrat subdivizije. \begin_inset Formula $\deg_{G}v=2$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $G$ \end_inset in \begin_inset Formula $H$ \end_inset sta homeomorfna, če sta subdivizija istega grafa. \end_layout \begin_layout Standard Kartezični produkt: \begin_inset Formula $V\left(G\square H\right)\coloneqq VG\times VH$ \end_inset , \begin_inset Formula $E\left(G\square H\right)\coloneqq\left\{ \left\{ \left(g,h\right),\left(g',h'\right)\right\} ;g=g'\wedge hh'\in EH\vee h=h'\wedge gg'\in EG\right\} $ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $\left(\mathcal{G},\square\right)$ \end_inset monoid, enota \begin_inset Formula $K_{1}$ \end_inset . \begin_inset Formula $Q_{n}\cong Q_{n-1}\square K_{2}=Q_{n-2}\square K_{2}^{\square,2}$ \end_inset \end_layout \begin_layout Standard Disjunktna unija: \begin_inset Formula $G$ \end_inset , \begin_inset Formula $H$ \end_inset disjunktna. \begin_inset Formula $V\left(G\cup H\right)\coloneqq VG\cup VH$ \end_inset , \begin_inset Formula $E\left(G\cup H\right)\coloneqq EG\cup EH$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $G,H$ \end_inset dvodelna \begin_inset Formula $\Rightarrow G\square H$ \end_inset dvodelen \end_layout \begin_layout Paragraph \begin_inset Formula $k-$ \end_inset povezan graf \end_layout \begin_layout Standard ima \begin_inset Formula $\geq k+1$ \end_inset vozlišč in ne vsebuje prerezne množice moči \begin_inset Formula $\Omega G$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $Y\subseteq EG$ \end_inset prerezna množica povezav \begin_inset Formula $\Leftrightarrow\Omega\left(G-Y\right)>\Omega G$ \end_inset \end_layout \begin_layout Standard Povezanost grafa: \begin_inset Formula $\kappa G=\max k$ \end_inset , da je \begin_inset Formula $G$ \end_inset \begin_inset Formula $k-$ \end_inset povezan. Primeri: \begin_inset Formula $\kappa K_{n}=n-1$ \end_inset , \begin_inset Formula $\kappa P_{n}=1$ \end_inset , \begin_inset Formula $\kappa C_{n}=2$ \end_inset , \begin_inset Formula $\kappa K_{n,m}=\min\left\{ n,m\right\} $ \end_inset , \begin_inset Formula $\kappa Q_{n}=n$ \end_inset , \begin_inset Formula $\kappa G\text{\ensuremath{\leq}}\delta G$ \end_inset \end_layout \begin_layout Standard Izrek (Menger): \begin_inset Formula $\left|VG\right|\geq k+1$ \end_inset : \begin_inset Formula $G$ \end_inset \begin_inset Formula $k-$ \end_inset povezan \begin_inset Formula $\Leftrightarrow\forall u,v\in VG,uv\not\in EG:\exists k$ \end_inset notranje disjunktnih \begin_inset Formula $u,v-$ \end_inset poti \end_layout \begin_layout Standard Graf je \begin_inset Formula $k-$ \end_inset povezan po povezavah, če ne vsebuje prerezne množice povezav moči \begin_inset Formula $\left|S\right|\Rightarrow G$ \end_inset ni hamiltonov. Primer: \begin_inset Formula $G$ \end_inset vsebuje prerezno vozlišče \begin_inset Formula $\Rightarrow G$ \end_inset ni hamiltonov. \end_layout \begin_layout Standard \begin_inset Formula $K_{n,m}$ \end_inset je hamiltonov \begin_inset Formula $\Leftrightarrow m=n$ \end_inset (za \begin_inset Formula $S$ \end_inset vzamemo \begin_inset Formula $\min\left\{ m,n\right\} $ \end_inset ) \end_layout \begin_layout Standard \begin_inset Formula $\left|VG\right|\geq3,\forall u,v\in VG:\deg_{G}u+\deg_{G}v\geq\left|VG\right|\Rightarrow G$ \end_inset hamil. \end_layout \begin_layout Standard Dirac: \begin_inset Formula $\left|VG\right|\geq3,\forall u\in VG:\deg_{G}u\geq\frac{\left|VG\right|}{2}\Rightarrow G$ \end_inset hamilton. \end_layout \begin_layout Paragraph Ravninski \end_layout \begin_layout Standard graf brez sekanja povezav narišemo v ravnino \end_layout \begin_layout Standard \begin_inset Formula $K_{2,3}$ \end_inset je ravninski, \begin_inset Formula $K_{3,3}$ \end_inset , \begin_inset Formula $K_{5}$ \end_inset , \begin_inset Formula $C_{5}\square C_{5}$ \end_inset in \begin_inset Formula $P_{5,2}$ \end_inset niso ravninski. \end_layout \begin_layout Standard Vložitev je ravninski graf z ustrezno risbo v ravnini. \end_layout \begin_layout Standard Lica so sklenjena območja vložitve brez vozlišč in povezav. \end_layout \begin_layout Standard \begin_inset Formula $G$ \end_inset lahko vložimo v ravnino \begin_inset Formula $\Leftrightarrow G$ \end_inset lahko vložimo na sfero. \end_layout \begin_layout Standard Dolžina lica \begin_inset Formula $F\sim lF$ \end_inset je št. povezav obhoda lica. \end_layout \begin_layout Standard Drevo je ravninski graf z enim licem dolžine \begin_inset Formula $2\left|ET\right|$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $\sum_{F\in FG}lF=2\left|EG\right|$ \end_inset , \begin_inset Formula $lF\geq gG$ \end_inset za ravninski \begin_inset Formula $G$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $2\left|EG\right|=\sum_{F\in FG}lF\geq\sum_{F\in FG}gG=gG\left|FG\right|$ \end_inset ( \begin_inset Formula $G$ \end_inset ravn.) \end_layout \begin_layout Standard \begin_inset Formula $G$ \end_inset ravninski \begin_inset Formula $\Rightarrow\left|EG\right|\geq\frac{gG}{2}$ \end_inset \begin_inset Formula $\left|FG\right|$ \end_inset \end_layout \begin_layout Standard Euler: \begin_inset Formula $\left|VG\right|-\left|EG\right|+\left|FG\right|=1+\Omega G$ \end_inset za ravninski \begin_inset Formula $G$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $G$ \end_inset ravninski, \begin_inset Formula $\left|VG\right|\geq3\Rightarrow\left|EG\right|\leq3\left|VG\right|-6$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $G$ \end_inset ravninski brez \begin_inset Formula $C_{3}$ \end_inset , \begin_inset Formula $\left|VG\right|\geq3\Rightarrow\left|EG\right|\text{\ensuremath{\leq2\left|VG\right|-4}}$ \end_inset \end_layout \begin_layout Standard Triangulacija je taka vložitev, da so vsa lica omejena s \begin_inset Formula $C_{3}$ \end_inset . \end_layout \begin_layout Standard V maksimalen ravninski graf ne moremo dodati povezave, da bi ostal ravninski. \begin_inset Formula $\sim$ \end_inset Ni pravi vpet podgraf ravn. grafa. \end_layout \begin_layout Standard \begin_inset Formula $K_{5}-e$ \end_inset je maksimalen ravninski graf \begin_inset Formula $\forall e\in EK_{5}$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $G$ \end_inset ravninski. NTSE: \begin_inset Formula $G$ \end_inset triangulacija \begin_inset Formula $\Leftrightarrow G$ \end_inset maksimalen ravninski \begin_inset Formula $\Leftrightarrow\left|EG\right|=3\left|VG\right|-6$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $G$ \end_inset ravninski \begin_inset Formula $\Leftrightarrow$ \end_inset vsaka subdivizija \begin_inset Formula $G$ \end_inset ravninska. \end_layout \begin_layout Standard Kuratovski: \begin_inset Formula $G$ \end_inset ravn. \begin_inset Formula $\Leftrightarrow$ \end_inset ne vsebuje subdivizije \begin_inset Formula $K_{5}$ \end_inset ali \begin_inset Formula $K_{3,3}$ \end_inset \end_layout \begin_layout Standard Wagner: \begin_inset Formula $G$ \end_inset ravn. \begin_inset Formula $\Leftrightarrow$ \end_inset niti \begin_inset Formula $K_{5}$ \end_inset niti \begin_inset Formula $K_{3,3}$ \end_inset nista njegova minorja \end_layout \begin_layout Standard Zunanje-ravninski ima vsa vozlišča na robu zunanjega lica. \end_layout \begin_layout Standard \begin_inset Formula $2-$ \end_inset povezan zunanje-ravninski je \series bold hamiltonov \series default . \end_layout \begin_layout Standard Zunanje-ravninski \begin_inset Formula $G$ \end_inset , \begin_inset Formula $\left|VG\right|\geq2$ \end_inset ima vozlišče stopnje \begin_inset Formula $\leq2$ \end_inset . \end_layout \begin_layout Paragraph Barvanje vozlišč \end_layout \begin_layout Standard je taka \begin_inset Formula $C:VG\to\left\{ 1..k\right\} \Leftrightarrow\forall uv\in EG:Cu\not=Cv$ \end_inset \end_layout \begin_layout Standard Kromatično število \begin_inset Formula $\chi G$ \end_inset je najmanjši \begin_inset Formula $k$ \end_inset , \begin_inset Formula $\ni:\exists$ \end_inset \begin_inset Formula $k-$ \end_inset barvanje \begin_inset Formula $G$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $\chi C_{n}=\begin{cases} 2 & ;n\text{ sod}\\ 3 & ;n\text{ lih} \end{cases}$ \end_inset , \begin_inset Formula $\chi G\leq\left|VG\right|,\chi G=\left|VG\right|\Leftrightarrow G\cong K_{n}$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $H$ \end_inset podgraf \begin_inset Formula $G\Rightarrow\chi G\geq\chi H$ \end_inset . \begin_inset Formula $\chi\text{bipartitni}=2$ \end_inset \end_layout \begin_layout Standard Barvni razred so vsa vozlišča iste barve. Je brez povezav \begin_inset Formula $\sim$ \end_inset \series bold neodvisna množica \series default . \end_layout \begin_layout Standard \begin_inset Formula $\chi G=k\Leftrightarrow\chi G\leq k\wedge\chi G\geq k$ \end_inset \end_layout \begin_layout Standard Klično št.: \begin_inset Formula $\omega G\coloneqq$ \end_inset \begin_inset Formula $\left|V\right|$ \end_inset najv. polnega podgr. v \begin_inset Formula $G$ \end_inset . \begin_inset Formula $\omega G\leq\chi G$ \end_inset . \end_layout \begin_layout Standard Trditev: \begin_inset Formula $\forall n\in\mathbb{N}\exists G\in\mathcal{G}\ni:\omega G=2\wedge\chi G=n$ \end_inset \end_layout \begin_layout Standard Požrešno barvanje: Vozlišča v poljubnem vrstnem redu barvamo z najnižno možno barvo. \end_layout \begin_layout Standard Vedno \begin_inset Formula $\exists$ \end_inset vrstni red, ki vrne barvanje s \begin_inset Formula $\chi G$ \end_inset barvami. \end_layout \begin_layout Standard \begin_inset Formula $\forall G\in\mathcal{G}:\chi G\leq\Delta G+1$ \end_inset , če \begin_inset Formula $G$ \end_inset ni regularen celo \begin_inset Formula $\chi G\leq\Delta G$ \end_inset \end_layout \begin_layout Standard Brooks: \begin_inset Formula $G$ \end_inset povezan, \begin_inset Formula $G$ \end_inset ni poln niti lihi cikel \begin_inset Formula $\Rightarrow\chi G\leq\Delta G$ \end_inset \end_layout \begin_layout Standard let \begin_inset Formula $d_{1}\geq\cdots\geq d_{n}$ \end_inset stopnje. \begin_inset Formula $\chi G=1+\max_{i=1}^{n}\min\left\{ d_{i},i-1\right\} $ \end_inset \end_layout \begin_layout Standard Spoj \begin_inset Formula $G\oplus H$ \end_inset je disjunktna unija \begin_inset Formula $G$ \end_inset , \begin_inset Formula $H$ \end_inset z vsemi pov. med njima \end_layout \begin_layout Standard Disjunktna unija je unija brez preseka. \end_layout \begin_layout Standard \begin_inset Formula $\chi\left(G\oplus H\right)=\chi G+\chi H$ \end_inset \end_layout \begin_layout Standard Ravninski graf ima \begin_inset Formula $\chi G\leq4$ \end_inset \end_layout \begin_layout Paragraph Barvanje povezav \end_layout \begin_layout Standard Povezavi s skupnim vozl. \begin_inset Formula $\Rightarrow$ \end_inset razl. barvi. \end_layout \begin_layout Standard Kromatični indeks \begin_inset Formula $\chi'G$ \end_inset je najm. št. barv za barv. pov. \begin_inset Formula $G$ \end_inset . \end_layout \begin_layout Standard \begin_inset Formula $\chi'C_{n}=\begin{cases} 2 & ;n\text{ sod}\\ 3 & ;n\text{ lih} \end{cases}$ \end_inset \end_layout \begin_layout Standard Vizing: \begin_inset Formula $\forall G\in\mathcal{G}:\Delta G\geq\chi'G\geq\Delta G+1$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $\chi G\in\left\{ \Delta G\text{ razred I.},\Delta G+1\text{ razred II.}\right\} $ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $K_{2k+1}\in$ \end_inset II., \begin_inset Formula $K_{2k}\in$ \end_inset I., bipartitni \begin_inset Formula $\in$ \end_inset I. \end_layout \begin_layout Paragraph Neodvisne množice \end_layout \begin_layout Standard \begin_inset Formula $I\subseteq VG$ \end_inset je neodvisna, če je podgraf, induciran z \begin_inset Formula $I$ \end_inset , brez povezav. \end_layout \begin_layout Standard Neodvisnostno št \begin_inset Formula $\alpha G$ \end_inset je moč največje neodvisne množice. \end_layout \begin_layout Standard \begin_inset Formula $\alpha K_{n}=1$ \end_inset , \begin_inset Formula $\alpha C_{n}=\lfloor\frac{n}{2}\rfloor$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $\alpha G\leq\sum_{i=1}^{k}\alpha H_{i}$ \end_inset , kjer so \begin_inset Formula $H_{i}$ \end_inset disjunktni inducirani podgr. \begin_inset Formula $G$ \end_inset . \end_layout \begin_layout Standard \begin_inset Formula $\forall G\in\mathcal{G}:\alpha G\cdot\chi G\geq\left|VG\right|$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $\frac{\left|VG\right|}{\chi G}\leq\alpha G\leq\left|VG\right|-\frac{\left|EG\right|}{\Delta G}$ \end_inset — zgornja in spodnja meja. \end_layout \begin_layout Standard \begin_inset Formula $Iu$ \end_inset je \begin_inset Formula $\alpha$ \end_inset poddrevesa s korenom \begin_inset Formula $u$ \end_inset v \begin_inset Formula $T$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $\alpha T=Ir=\max\left\{ 1+\sum_{u\text{ sinovi }r}Iu,\sum_{u\text{ vnuki }r}Iu\right\} $ \end_inset \end_layout \begin_layout Paragraph Dominantne množice \end_layout \begin_layout Standard Neodvisna \begin_inset Formula $I\subseteq G$ \end_inset je maksimalna \begin_inset Formula $\sim\nexists S\text{ neodvisna}\subseteq G\ni:I\subset S\sim$ \end_inset ni prava \begin_inset Formula $\subset$ \end_inset neodv. mn. \end_layout \begin_layout Standard Dominantna množica je maksimalna neodvisna, kjer ima vsako vozlišče iz \begin_inset Formula $G\setminus I$ \end_inset soseda v \begin_inset Formula $I$ \end_inset . \end_layout \begin_layout Standard \begin_inset Formula $D\subseteq VG$ \end_inset dominira \begin_inset Formula $X\subseteq VG$ \end_inset , če je vsako vozlišče iz \begin_inset Formula $X$ \end_inset v \begin_inset Formula $D$ \end_inset ali pa ima soseda v \begin_inset Formula $D$ \end_inset . \end_layout \begin_layout Standard \begin_inset Formula $N_{G}\left(u\right)=$ \end_inset sosedje \begin_inset Formula $u$ \end_inset v \begin_inset Formula $G$ \end_inset , \begin_inset Formula $N_{G}\left[u\right]=N_{G}\left(u\right)\cup\left\{ u\right\} $ \end_inset zap. sos. \begin_inset Formula $u$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $N_{G}\left[D\right]=\bigcup_{u\in D}N_{G}\left[u\right]$ \end_inset zaprta soseščina množice \begin_inset Formula $D$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $D$ \end_inset dominira \begin_inset Formula $X\sim X\subseteq N_{G}\left[D\right]$ \end_inset . \end_layout \begin_layout Standard \begin_inset Formula $D$ \end_inset dominira \begin_inset Formula $VG\sim D$ \end_inset dominantna množica \begin_inset Formula $G$ \end_inset . \end_layout \begin_layout Standard Dominacijsko število \begin_inset Formula $\gamma G=$ \end_inset moč največje dom. mn. \end_layout \begin_layout Standard Vsaka maksimalna neodvisna mn. \begin_inset Formula $G$ \end_inset je dom. mn. \begin_inset Formula $G$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $\gamma K_{n}=1$ \end_inset , \begin_inset Formula $\gamma C_{n}=\lceil\frac{n}{3}\rceil$ \end_inset , \begin_inset Formula $\gamma P=3$ \end_inset \end_layout \begin_layout Standard Za vsak graf brez izoliranih vozlišč \begin_inset Formula $\lceil\frac{\left|VG\right|}{\Delta G+1}\rceil\leq\gamma G\leq\lfloor\frac{\left|VG\right|}{2}\rfloor$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $X$ \end_inset je 2-pakiranje \begin_inset Formula $G$ \end_inset , če \begin_inset Formula $\forall x,y\in X:x\not=y\Rightarrow d_{G}\left(x,y\right)\geq3$ \end_inset zdb \begin_inset Formula $\forall x,y\in X:x\not=y\Rightarrow N_{G}x\cap N_{G}y=\emptyset$ \end_inset \end_layout \begin_layout Standard Moč največjega 2-pakiranja je 2-pakirno število \begin_inset Formula $\rho G$ \end_inset . \end_layout \begin_layout Standard \begin_inset Formula $G$ \end_inset povezan \begin_inset Formula $\Rightarrow\gamma G\geq\rho G$ \end_inset \end_layout \begin_layout Standard Dominantna \begin_inset Formula $X$ \end_inset je popolna koda \begin_inset Formula $G\Leftrightarrow\bigcup_{u\in X}N_{G}\left[u\right]=VG$ \end_inset \end_layout \begin_layout Standard Če graf premore popolno kodo \begin_inset Formula $\Rightarrow\gamma G=\rho G$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $H$ \end_inset vpet podgraf \begin_inset Formula $G\Rightarrow\gamma G\leq\gamma H$ \end_inset \end_layout \begin_layout Standard Povezan \begin_inset Formula $G$ \end_inset premore vpeto drevo \begin_inset Formula $T\ni:\gamma G=\gamma T$ \end_inset . Dokaz: odstrani vse povezave, kjer \begin_inset Formula $G-e$ \end_inset ohrani \begin_inset Formula $\gamma$ \end_inset in povezanost. \end_layout \begin_layout Standard \begin_inset Formula $\left|VG\right|\geq1\Rightarrow\gamma G\leq\chi\overline{G}$ \end_inset \end_layout \begin_layout Standard Povezana dom. mn. inducira povez. podgraf. — \begin_inset Formula $\gamma_{c}$ \end_inset \end_layout \begin_layout Standard Neodvisna dom. mn. inducira podgraf brez povezav — \begin_inset Formula $\gamma_{i}$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $X$ \end_inset je celotna dom. mn. \begin_inset Formula $\Leftrightarrow\forall v\in VG:N_{G}\left(v\right)\cap X\not=\emptyset$ \end_inset — \begin_inset Formula $\gamma_{t}$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $G$ \end_inset brez izol. vozl.: \begin_inset Formula $\gamma G\leq\gamma_{t}G\leq2\gamma G$ \end_inset \end_layout \begin_layout Paragraph Algebrske strukture z eno operacijo \end_layout \begin_layout Standard Grupoid: notranjost, polgrupa: asociativen grupoid, monoid: polgrupa z enoto \end_layout \begin_layout Standard Grupa: \begin_inset Formula $\forall a\in A\exists a^{-1}\in A\ni:a\cdot a^{-1}=a^{-1}\cdot a=e$ \end_inset \end_layout \begin_layout Standard Potence v monoidu: \begin_inset Formula $n\in\mathbb{N}_{0}$ \end_inset . \begin_inset Formula $a^{0}=e$ \end_inset , \begin_inset Formula $a^{n}=a\cdot a^{n-1}$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $\left(a\cdot b\right)^{-1}=b^{-1}\cdot a^{-1}$ \end_inset , \begin_inset Formula $a^{n}\cdot a^{m}=a^{n+m},\left(a^{n}\right)^{m}=a^{nm}$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $\left(a^{-1}\right)^{n}=\left(a^{n}\right)^{-1}$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $\left(\mathbb{Z}_{m},+_{m}\right)$ \end_inset grupa, \begin_inset Formula $\left(\mathbb{Z}_{m},\cdot_{n}\right)$ \end_inset monoid \end_layout \begin_layout Standard \begin_inset Formula $k\in\mathbb{Z}_{n}$ \end_inset obrnljiv v \begin_inset Formula $\left(\mathbb{Z}_{n},\cdot_{n}\right)\Leftrightarrow k\perp n\sim\gcd\left\{ k,n\right\} =1$ \end_inset \end_layout \begin_layout Standard Komutativni grupi pravimo abelova. \end_layout \begin_layout Standard Cayleyeva tabela je predpis za grupoid \begin_inset Formula $\cdot:A^{2}\to A$ \end_inset . \end_layout \begin_layout Standard red \begin_inset Formula $a$ \end_inset je najmanjši \begin_inset Formula $n\in\mathbb{N}\ni:a^{n}=e$ \end_inset oz. \begin_inset Formula $\infty$ \end_inset , če ne obstaja. \end_layout \begin_layout Standard Def.: \begin_inset Formula $H\subseteq G$ \end_inset podgrupa, če je grupa za isto operacijo. \end_layout \begin_layout Standard Izrek: \begin_inset Formula $H\subseteq G$ \end_inset podgrupa \begin_inset Formula $\Leftrightarrow\forall x,y\in H:x^{-1}y\in H$ \end_inset \end_layout \begin_layout Standard Trivialni podgrupi \begin_inset Formula $G$ \end_inset sta \begin_inset Formula $\left\{ e\right\} $ \end_inset in \begin_inset Formula $G$ \end_inset . \begin_inset space \hfill{} \end_inset Ciklična podgrupa: \end_layout \begin_layout Standard \begin_inset Formula $\left\langle a\right\rangle \coloneqq\left\{ a^{n};\forall n\in\mathbb{Z}\right\} $ \end_inset je podgrupa v \begin_inset Formula $G$ \end_inset za \begin_inset Formula $a\in\text{grupa }G$ \end_inset \end_layout \begin_layout Standard Center grupe: \begin_inset Formula $ZG=\left\{ a\in G;\forall x\in G:ax=xa\right\} $ \end_inset . \end_layout \begin_layout Standard \begin_inset Formula $\left(ZG,\cdot\right)$ \end_inset je podgrupa grupe \begin_inset Formula $\left(G,\cdot\right)$ \end_inset . \end_layout \begin_layout Paragraph Permutacijske grupe \end_layout \begin_layout Standard Permutacija je bijekcija \begin_inset Formula $A\to A$ \end_inset . \end_layout \begin_layout Standard perm. gr. so permutacije \begin_inset Formula $A$ \end_inset , ki tvorijo grupo za \begin_inset Formula $\circ$ \end_inset . \end_layout \begin_layout Standard Polna simetrična grupa \begin_inset Formula $S_{n}\coloneqq\left\{ \pi:\left\{ 1..n\right\} \to\left\{ 1..n\right\} ;\pi\text{ bijekcija}\right\} $ \end_inset \end_layout \begin_layout Standard Alternirajoča grupa \begin_inset Formula $A_{n}\coloneqq\left\{ \pi\in S_{n};\pi\text{ soda}\right\} $ \end_inset \end_layout \begin_layout Standard Permutacija kot produkt disjunktnih ciklov dolžin \begin_inset Formula $l_{1},\dots,l_{n}$ \end_inset je soda, če je \begin_inset Formula $\left(l_{1}-1\right)+\cdots+\left(l_{n}-1\right)$ \end_inset sod. \end_layout \begin_layout Standard \begin_inset Formula $\left|S_{n}\right|=n!$ \end_inset , \begin_inset Formula $\left|A_{n}\right|=\frac{n!}{2}$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $\left(G,\circ\right)$ \end_inset , \begin_inset Formula $\left(H,*\right)$ \end_inset grupi. \begin_inset Formula $f:G\to H$ \end_inset je hm \begin_inset Formula $\varphi\Leftrightarrow\forall x,y\in G:f\left(x\circ y\right)=fx*fy$ \end_inset . \begin_inset Formula $f$ \end_inset je še celo im \begin_inset Formula $\varphi\Leftrightarrow f$ \end_inset bijekcija. \end_layout \begin_layout Standard Grupi sta izomorfni \begin_inset Formula $\sim\text{\ensuremath{\exists}}$ \end_inset im \begin_inset Formula $\varphi$ \end_inset med njima: \begin_inset Formula $G\approx H$ \end_inset \end_layout \begin_layout Standard Vsaka grupa je izomorfna neki permutacijski grupi \end_layout \begin_layout Paragraph Odseki in podgrupe edinke \end_layout \begin_layout Standard \begin_inset Formula $\left(G,\circ\right)$ \end_inset grupa, \begin_inset Formula $H\subseteq G$ \end_inset . za \begin_inset Formula $a\in G$ \end_inset : \begin_inset Formula $aH=\left\{ ah;h\in H\right\} ,Ha=\left\{ ha;h\in H\right\} $ \end_inset . Za \begin_inset Formula $H$ \end_inset podgrupo pravimo \begin_inset Formula $aH$ \end_inset levi odsek \begin_inset Formula $H$ \end_inset in \begin_inset Formula $Ha$ \end_inset desni. Velja: \begin_inset Formula $a\in aH$ \end_inset , \begin_inset Formula $aH=H\Leftrightarrow a\in H$ \end_inset , \begin_inset Formula $aH=bH\nabla aH\cap bH=\emptyset$ \end_inset , \begin_inset Formula $aH=bH\Leftrightarrow a^{-1}b\in H$ \end_inset , \begin_inset Formula $\left|aH\right|=\left|bH\right|$ \end_inset , \begin_inset Formula $aH=Ha\Leftrightarrow H=aHa^{-1}$ \end_inset , \begin_inset Formula $aH\subseteq G\Leftrightarrow a\in H$ \end_inset \end_layout \begin_layout Standard general linear \begin_inset Formula $GL_{2}\mathbb{R}=\left\{ A\in M_{2,2}\mathbb{R},\det A\not=0\right\} $ \end_inset \end_layout \begin_layout Standard special linear \begin_inset Formula $SL_{2}\mathbb{R}=\left\{ A\in M_{2,2}\mathbb{R},\det A=1\right\} $ \end_inset \end_layout \begin_layout Standard Lagrange: \begin_inset Formula $H$ \end_inset podgrupa končne grupe \begin_inset Formula $G\Rightarrow\left|H\right|\text{ deli }\left|G\right|$ \end_inset in število različnih levih/desnih odeskov po \begin_inset Formula $H$ \end_inset je \begin_inset Formula $\frac{\left|G\right|}{\left|H\right|}$ \end_inset . \end_layout \begin_layout Standard \begin_inset Formula $a\in$ \end_inset končne grupe \begin_inset Formula $G\Rightarrow$ \end_inset red \begin_inset Formula $a$ \end_inset deli \begin_inset Formula $\left|G\right|$ \end_inset \end_layout \begin_layout Paragraph Podgrupe edinke in faktorske grupe \end_layout \begin_layout Standard \begin_inset Formula $H$ \end_inset podgrupa \begin_inset Formula $G$ \end_inset je edinka \begin_inset Formula $\Leftrightarrow\forall a\in G:aH=Ha\sim aHa^{-1}=H$ \end_inset \end_layout \begin_layout Standard Podgrupa konjugiranka \begin_inset Formula $H^{a}\coloneqq aHa^{-1}$ \end_inset . \end_layout \begin_layout Standard \begin_inset Formula $H\triangleleft G\sim H$ \end_inset edinka v \begin_inset Formula $G$ \end_inset \begin_inset Formula $\Leftrightarrow\forall a\in G:H^{A}=H$ \end_inset \end_layout \begin_layout Standard V Abelovi grupi je vsaka podgrupa edinka. \end_layout \begin_layout Standard Center je podgrupa edinka. \end_layout \begin_layout Standard \begin_inset Formula $G/H\coloneqq\left\{ aH:a\in G\right\} $ \end_inset z oper. \begin_inset Formula $\left(aH\right)*\left(bH\right)=\left(ab\right)H$ \end_inset \end_layout \begin_layout Standard Izrek o faktorskih grupah: \begin_inset Formula $H\triangleleft G\Rightarrow\left(G/H,*\right)$ \end_inset grupa \end_layout \begin_layout Paragraph Kolobarji in polja \end_layout \begin_layout Standard \begin_inset Formula $\left(R,+,\cdot\right)\text{kolobar}\Rightarrow$ \end_inset \begin_inset Formula $\left(R,+\right)$ \end_inset abelova grupa, \begin_inset Formula $\left(R,\cdot\right)$ \end_inset polgrupa, distributivnost. \end_layout \begin_layout Standard Kolobar je komutativen, če je \begin_inset Formula $\cdot$ \end_inset komutativna. \end_layout \begin_layout Standard Kolobar je z enoto, če obstaja enota za \begin_inset Formula $\cdot$ \end_inset . \end_layout \begin_layout Standard Direktna vsota kolobarjev \begin_inset Formula $\left(R\oplus S,+,\cdot\right)$ \end_inset je kolobar. \begin_inset Formula $R\oplus S=R\times S$ \end_inset , \begin_inset Formula $+$ \end_inset in \begin_inset Formula $\cdot$ \end_inset po komponentah. \end_layout \begin_layout Standard \begin_inset Formula $R$ \end_inset in \begin_inset Formula $S$ \end_inset komutativna \begin_inset Formula $\Rightarrow R\oplus S$ \end_inset komutativen. \end_layout \begin_layout Standard \begin_inset Formula $R$ \end_inset in \begin_inset Formula $S$ \end_inset z enoto \begin_inset Formula $\Rightarrow R\oplus S$ \end_inset z enoto. \end_layout \begin_layout Standard \begin_inset Formula $R$ \end_inset kolobar. \begin_inset Formula $S\subseteq R$ \end_inset je za podedovani operaciji kolobar, če je \begin_inset Formula $\left(S,+,\cdot\right)$ \end_inset kolobar. Izrek: \begin_inset Formula $S$ \end_inset podkolobar \begin_inset Formula $\Leftrightarrow0\in S$ \end_inset in zaprta za \begin_inset Formula $-,\cdot$ \end_inset \end_layout \begin_layout Standard Center kolobarja: \begin_inset Formula $ZR=\left\{ a\in R;\forall x\in R:ax=xa\right\} $ \end_inset je podk. \end_layout \begin_layout Paragraph Delitelji niča in celi kolobarji \end_layout \begin_layout Standard \begin_inset Formula $\left(\mathbb{Z}_{n},+_{n},\cdot_{n}\right)$ \end_inset je vedno kol. \end_layout \begin_layout Standard Def.: Če v kolobarju velja \begin_inset Formula $ab=0$ \end_inset in \begin_inset Formula $a\not=0$ \end_inset in \begin_inset Formula $b\not=0$ \end_inset , sta \begin_inset Formula $a$ \end_inset in \begin_inset Formula $b$ \end_inset delitelja niča. \end_layout \begin_layout Standard Pravilo krajšanja: \begin_inset Formula $\forall a,b,c\in R,a\not=0:ab=ac\Rightarrow b=c$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $R$ \end_inset cel \begin_inset Formula $\Leftrightarrow$ \end_inset komutativen z enoto \begin_inset Formula $1\not=0$ \end_inset brez deliteljev niča. \end_layout \begin_layout Standard Za komutativen z enoto \begin_inset Formula $1\not=0$ \end_inset velja: cel \begin_inset Formula $\Leftrightarrow$ \end_inset velja prav. krajš. \end_layout \begin_layout Standard \begin_inset Formula $\left(R,+,\cdot\right)$ \end_inset z enoto \begin_inset Formula $1\not=0$ \end_inset je polje, če je \begin_inset Formula $\left(R\setminus\left\{ 0\right\} ,\cdot\right)$ \end_inset abelova g. \end_layout \begin_layout Standard \begin_inset Formula $\left(R,+,\cdot\right)$ \end_inset z enoto \begin_inset Formula $1\not=0$ \end_inset je obseg, če je \begin_inset Formula $\left(R\setminus\left\{ 0\right\} ,\cdot\right)$ \end_inset grupa. \end_layout \begin_layout Standard Vsako polje je cel kolobar. \end_layout \begin_layout Standard Polje je cel kolobar z multiplik. inverzi za vse neničelne. \end_layout \begin_layout Standard Končen cel kolobar \begin_inset Formula $\Rightarrow$ \end_inset polje. \end_layout \begin_layout Standard \begin_inset Formula $\forall n\in\mathbb{N}\setminus\left\{ 1\right\} :\mathbb{Z}_{n}$ \end_inset cel \begin_inset Formula $\Leftrightarrow$ \end_inset \begin_inset Formula $\mathbb{Z}_{n}$ \end_inset polje \begin_inset Formula $\Leftrightarrow$ \end_inset \begin_inset Formula $n$ \end_inset praštevilo \end_layout \begin_layout Standard \begin_inset Formula $S\subseteq$ \end_inset polje \begin_inset Formula $R$ \end_inset je podpolje za poded. operaciji, če je \begin_inset Formula $S$ \end_inset polje. Zadošča preveriti \begin_inset Formula $1\in S$ \end_inset , zaprtost za \begin_inset Formula $-$ \end_inset in deljenje z nenič.ž \end_layout \begin_layout Standard \begin_inset Formula $n\cdot'a$ \end_inset naj pomeni \begin_inset Formula $a+\cdots+a$ \end_inset \begin_inset Formula $n$ \end_inset -krat za \begin_inset Formula $n\in\mathbb{N}$ \end_inset \end_layout \begin_layout Standard Karakteristika kolobarja je najmanjši \begin_inset Formula $n\in N\ni:\forall a\in R:n\cdot'a=0$ \end_inset . Če ne obstaja, pravimo char \begin_inset Formula $R=0$ \end_inset . \end_layout \begin_layout Standard Izrek: Če je red1 \begin_inset Formula $=n\Rightarrow$ \end_inset char \begin_inset Formula $R=n$ \end_inset \end_layout \begin_layout Standard Izrek: Za cel kolobar \begin_inset Formula $R$ \end_inset je char \begin_inset Formula $R=0$ \end_inset ali char \begin_inset Formula $R=$ \end_inset praštevilo \end_layout \begin_layout Paragraph Ideali \end_layout \begin_layout Standard \begin_inset Formula $S$ \end_inset podkolobar \begin_inset Formula $R$ \end_inset je ideal \begin_inset Formula $R\Leftrightarrow\forall r\in R,s\in S:rs,sr\in S$ \end_inset \end_layout \begin_layout Standard Primer: večkratniki \begin_inset Formula $n$ \end_inset so za fiksen \begin_inset Formula $n$ \end_inset ideal v \begin_inset Formula $\mathbb{Z}$ \end_inset . \end_layout \begin_layout Standard \begin_inset Formula $I\subseteq R$ \end_inset je ideal \begin_inset Formula $\Leftrightarrow0\in I$ \end_inset , zaprt za \begin_inset Formula $-$ \end_inset , zaprt za zunanje množ. \end_layout \begin_layout Standard Operaciji nad ideali: \begin_inset Formula $I\overset{+}{\cdot}J=\left\{ i\overset{+}{\cdot}j;\forall i\in I,j\in J\right\} $ \end_inset \end_layout \begin_layout Standard Za ideala \begin_inset Formula $I,J$ \end_inset v \begin_inset Formula $R$ \end_inset sta \begin_inset Formula $I+J$ \end_inset in \begin_inset Formula $I\cdot J$ \end_inset zopet ideala v \begin_inset Formula $R$ \end_inset . \end_layout \begin_layout Standard V aditivne odseke \begin_inset Formula $R/I=\left\{ a+I;\forall a\in R\right\} $ \end_inset vpeljemo operaciji \begin_inset Formula $\left(a+I\right)\overset{+}{\cdot}\left(b+I\right)=\left(a\overset{+}{\cdot}b\right)I$ \end_inset . Če je \begin_inset Formula $I$ \end_inset ideal v \begin_inset Formula $R$ \end_inset , je \begin_inset Formula $R/I$ \end_inset za operaciji kolobar. \end_layout \begin_layout Standard \begin_inset ERT status open \begin_layout Plain Layout \backslash end{multicols} \end_layout \end_inset \end_layout \end_body \end_document