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 /3.3.4.lyx | |
| parent | 16ccda6c459c0fd7ca2081e9d541124c28b0c556 (diff) | |
Changed layout for more manageable volumes
Diffstat (limited to '3.3.4.lyx')
| -rw-r--r-- | 3.3.4.lyx | 781 |
1 files changed, 0 insertions, 781 deletions
diff --git a/3.3.4.lyx b/3.3.4.lyx deleted file mode 100644 index 1c06b60..0000000 --- a/3.3.4.lyx +++ /dev/null @@ -1,781 +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 -exerc1[M10] -\end_layout - -\end_inset - -To what does the spectral test reduce in -\emph on -one -\emph default - dimension? - (In other words, - what happens when -\begin_inset Formula $t=1$ -\end_inset - -?) -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - -In this case -\begin_inset Formula $\nu_{1}^{-1}$ -\end_inset - - is the maximum distance between points in -\begin_inset Formula $\{x/m\}_{x=0}^{m-1}$ -\end_inset - -, - which is -\begin_inset Formula $m^{-1}$ -\end_inset - -, - so -\begin_inset Formula $\nu_{1}=m$ -\end_inset - -. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc4[M23] -\end_layout - -\end_inset - -Let -\begin_inset Formula $u_{11}$ -\end_inset - -, - -\begin_inset Formula $u_{12}$ -\end_inset - -, - -\begin_inset Formula $u_{21}$ -\end_inset - -, - -\begin_inset Formula $u_{22}$ -\end_inset - - be elements of a -\begin_inset Formula $2\times2$ -\end_inset - - integer matrix such that -\begin_inset Formula $u_{11}+au_{12}\equiv u_{21}+au_{22}\equiv0\pmod m$ -\end_inset - - and -\begin_inset Formula $u_{11}u_{22}-u_{21}u_{12}=m$ -\end_inset - -. -\end_layout - -\begin_layout Enumerate -Prove that all integer solutions -\begin_inset Formula $(y_{1},y_{2})$ -\end_inset - - to the congruence -\begin_inset Formula $y_{1}+ay_{2}\equiv0\pmod m$ -\end_inset - - have the form -\begin_inset Formula $(y_{1},y_{2})=(x_{1}u_{11}+x_{2}u_{21},x_{1}u_{12}+x_{2}u_{22})$ -\end_inset - - for integer -\begin_inset Formula $x_{1}$ -\end_inset - -, - -\begin_inset Formula $x_{2}$ -\end_inset - -. -\end_layout - -\begin_layout Enumerate -If, - in addition, - -\begin_inset Formula $2|u_{11}u_{21}+u_{12}u_{22}|\leq u_{11}^{2}+u_{12}^{2}\leq u_{21}^{2}+u_{22}^{2}$ -\end_inset - -, - prove that -\begin_inset Formula $(y_{1},y_{2})=(u_{11},u_{12})$ -\end_inset - - minimizes -\begin_inset Formula $y_{1}^{2}+y_{2}^{2}$ -\end_inset - - over all nonzero solutions to the congruence. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - -Assume -\begin_inset Formula $a\in\mathbb{Z}$ -\end_inset - - and -\begin_inset Formula $m\in\mathbb{N}^{*}$ -\end_inset - -. -\end_layout - -\begin_layout Enumerate -Clearly all pairs of integers -\begin_inset Formula $(p,q)$ -\end_inset - - can be written as -\begin_inset Formula $(p,q)=z_{1}(m,0)+z_{2}(-a,1)+z_{3}(1,0)$ -\end_inset - - for some -\begin_inset Formula $z_{1},z_{2},z_{3}\in\mathbb{Z}$ -\end_inset - - with -\begin_inset Formula $0\leq z_{3}<m$ -\end_inset - -. - Moreover, - solutions to the congruence are precisely those pairs with -\begin_inset Formula $z_{3}=0$ -\end_inset - -, - and we just have to prove that -\begin_inset Formula $(m,0)$ -\end_inset - - and -\begin_inset Formula $(-a,1)$ -\end_inset - - can be expressed as an integer linear combination of -\begin_inset Formula $(u_{11},u_{12})$ -\end_inset - - and -\begin_inset Formula $(u_{21},u_{22})$ -\end_inset - -. - -\end_layout - -\begin_deeper -\begin_layout Standard -For -\begin_inset Formula $(m,0)$ -\end_inset - -, - -\begin_inset Formula $u_{22}(u_{11},u_{12})-u_{12}(u_{21},u_{22})=(m,0)$ -\end_inset - -. - For -\begin_inset Formula $(a,-1)$ -\end_inset - -, - if -\begin_inset Formula $j,k\in\mathbb{Z}$ -\end_inset - - are such that -\begin_inset Formula $u_{11}=jm-au_{12}$ -\end_inset - - and -\begin_inset Formula $u_{21}=km-au_{22}$ -\end_inset - -, - we can expand to get -\begin_inset Formula $m=u_{11}u_{22}-u_{21}u_{12}=ju_{22}m-ku_{12}m$ -\end_inset - -, - so -\begin_inset Formula $ju_{22}-ku_{12}=1$ -\end_inset - -, - and then -\begin_inset Formula $ju_{21}-ku_{11}=-aju_{22}+aku_{12}=-a(ju_{22}-ku_{12})=-a$ -\end_inset - -, - so -\begin_inset Formula $(-a,1)=-k(u_{11},u_{12})+j(u_{21},u_{22})$ -\end_inset - -. -\end_layout - -\end_deeper -\begin_layout Enumerate -If -\begin_inset Formula $x_{1},x_{2}\in\mathbb{Z}$ -\end_inset - - are not both 0, - then -\begin_inset Formula -\begin{multline*} -(x_{1}u_{11}+x_{2}u_{21})^{2}+(x_{1}u_{12}+x_{2}u_{22})^{2}=\\ -=x_{1}^{2}(u_{11}^{2}+u_{12}^{2})+x_{2}^{2}(u_{21}^{2}+u_{22}^{2})+2x_{1}x_{2}(u_{11}u_{21}+u_{21}u_{22}). -\end{multline*} - -\end_inset - -If -\begin_inset Formula $x_{1}x_{2}(u_{11}u_{21}+u_{21}u_{22})\geq0$ -\end_inset - -, - then this is greater or equal to -\begin_inset Formula -\[ -x_{1}^{2}(u_{11}^{2}+u_{12}^{2})+x_{2}^{2}(u_{21}^{2}+u_{22}^{2})\geq(x_{1}^{2}+x_{2}^{2})(u_{11}^{2}+u_{12}^{2})\geq u_{11}^{2}+u_{12}^{2}. -\] - -\end_inset - -Otherwise -\begin_inset Formula $x_{1},x_{2}\neq0$ -\end_inset - - and, - if -\begin_inset Formula $|x_{1}|\leq|x_{2}|$ -\end_inset - -, - then the above is greater than or equal to -\begin_inset Formula -\[ -x_{1}^{2}(u_{11}^{2}+u_{12}^{2}-2(u_{11}u_{21}+u_{21}u_{22}))+x_{2}^{2}(u_{21}^{2}+u_{22}^{2})\geq x_{2}^{2}(u_{21}^{2}+u_{22}^{2})\geq u_{11}^{2}+u_{12}^{2}, -\] - -\end_inset - -whereas the case with -\begin_inset Formula $|x_{1}|\geq|x_{2}|$ -\end_inset - - is analogous. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc15[M20] -\end_layout - -\end_inset - -Let -\begin_inset Formula $U$ -\end_inset - - be an integer vector satisfying (15). - How many of the -\begin_inset Formula $(t-1)$ -\end_inset - --dimensional hyperplanes defined by -\begin_inset Formula $U$ -\end_inset - - intersect the unit hypercube -\begin_inset Formula $\{(x_{1},\dots,x_{t})\mid0\leq x_{j}<1\text{ for }1\leq j\leq t\}$ -\end_inset - -? - (This is approximately the number of hyperplanes in the family that will suffice to cover -\begin_inset Formula $L_{0}$ -\end_inset - -.) -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - -The hyperplanes are defined by -\begin_inset Formula $\{\{X\mid X\cdot U=q\}\}_{q\in\mathbb{Z}}$ -\end_inset - -, - so we need to find the maximum and minimum integer values for -\begin_inset Formula $X\cdot U$ -\end_inset - - when -\begin_inset Formula $X\in[0,1)^{n}$ -\end_inset - -, - which exist because -\begin_inset Formula $0\cdot U=0\in\mathbb{Z}$ -\end_inset - -. - The maximum and minimum real values when -\begin_inset Formula $X\in[0,1]^{n}$ -\end_inset - - are, - respectively, - -\begin_inset Formula $M\coloneqq u_{1}\frac{1+\text{sgn}u_{1}}{2}+\dots+u_{t}\frac{1+\text{sgn}u_{t}}{2}$ -\end_inset - - and -\begin_inset Formula $m\coloneqq u_{1}\frac{1-\text{sgn}u_{1}}{2}+\dots+u_{t}\frac{1-\text{sgn}u_{t}}{2}$ -\end_inset - -, - which happen to be integers, - so we have -\begin_inset Formula -\[ -M-m+1=u_{1}\text{sgn}u_{1}+\dots+u_{t}\text{sgn}u_{t}+1=|u_{1}|+\dots+|u_{t}|+1 -\] - -\end_inset - -hyperplanes. -\end_layout - -\begin_layout Standard -However, - one of these hyperplanes might only cover points in -\begin_inset Formula $[0,1]^{n}\setminus[0,1)^{n}$ -\end_inset - -. - This happens precisely when -\begin_inset Formula $(1,\dots,1)\cdot U=u_{1}+\dots+u_{t}$ -\end_inset - - is either -\begin_inset Formula $M$ -\end_inset - - or -\begin_inset Formula $m$ -\end_inset - -, - that is, - when all of the -\begin_inset Formula $u_{i}$ -\end_inset - - are nonnegative or nonpositive. - Thus, - the actual number of hyperplanes is -\begin_inset Formula -\[ -|u_{1}|+\dots+|u_{t}|+1-[u_{1},\dots,u_{t}\leq0]-[u_{1},\dots,u_{t}\geq0]. -\] - -\end_inset - - -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc19[HM25] -\end_layout - -\end_inset - -Suppose step S5 were changed slightly, - so that a transformation with -\begin_inset Formula $q=1$ -\end_inset - - would be performed when -\begin_inset Formula $2V_{i}\cdot V_{j}=V_{j}\cdot V_{j}$ -\end_inset - -. - (Thus, - -\begin_inset Formula $q=\lfloor(V_{i}\cdot V_{j}/V_{j}\cdot V_{j})+\frac{1}{2}\rfloor$ -\end_inset - - whenever -\begin_inset Formula $i\neq j$ -\end_inset - -.) Would it still be possible for Algorithm S to get into an infinite loop? -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - -No. - If -\begin_inset Formula $2|V_{i}\cdot V_{j}|>V_{j}\cdot V_{j}$ -\end_inset - - in some step, - then -\begin_inset Formula -\[ -(V_{i}-qV_{j})\cdot(V_{i}-qV_{j})=V_{i}\cdot V_{i}-2qV_{i}\cdot V_{j}+V_{j}\cdot V_{j}<V_{i}\cdot V_{i}, -\] - -\end_inset - -because -\begin_inset Formula $q$ -\end_inset - - has the same sign as -\begin_inset Formula $V_{i}\cdot V_{j}$ -\end_inset - - and therefore -\begin_inset Formula $V_{j}\cdot V_{j}<2|V_{i}\cdot V_{j}|\leq2qV_{i}\cdot V_{j}$ -\end_inset - -, - so -\begin_inset Formula $V_{i}\cdot V_{i}$ -\end_inset - - decreases and, - since it is an integer, - it cannot decrease for infinitely many steps. - Thus, - an infinite loop would eventually only contain steps where -\begin_inset Formula $2V_{i}\cdot V_{j}=V_{j}\cdot V_{j}$ -\end_inset - -, - which are the ones we allow now, - and since there are only finitely many integer vectors with a given norm, - -\begin_inset Formula $V$ -\end_inset - - would have to repeat at some point. - However, - in these cases -\begin_inset Formula $q=1$ -\end_inset - -, - so the steps are equivalent to multiplying -\begin_inset Formula $V$ -\end_inset - - by an elementary matrix with 1s at the diagonal and at some other value and 0s everywhere else. - These matrices cannot result in an identity matrix when multiplying them because they don't have negative entries. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc32[M21] -\end_layout - -\end_inset - -Let -\begin_inset Formula $m_{1}=2^{31}-1$ -\end_inset - - and -\begin_inset Formula $m_{2}=2^{31}-249$ -\end_inset - - be the moduli of generator (38). -\end_layout - -\begin_layout Enumerate -Show that if -\begin_inset Formula $U_{n}=(X_{n}/m_{1}-Y_{n}/m_{2})\bmod1$ -\end_inset - -, - we have -\begin_inset Formula $U_{n}\approx Z_{n}/m_{1}$ -\end_inset - -. -\end_layout - -\begin_layout Enumerate -Let -\begin_inset Formula $W_{0}=(X_{0}m_{2}-Y_{0}m_{1})\bmod m$ -\end_inset - - and -\begin_inset Formula $W_{n+1}=aW_{n}\bmod m$ -\end_inset - -, - where -\begin_inset Formula $a$ -\end_inset - - and -\begin_inset Formula $m$ -\end_inset - - have the values stated in the text following (38). - Prove that there is a simple relation between -\begin_inset Formula $W_{n}$ -\end_inset - - and -\begin_inset Formula $U_{n}$ -\end_inset - -. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - - -\end_layout - -\begin_layout Enumerate -\begin_inset Formula $Z_{n}/m_{1}=(X_{n}/m_{1}-Y_{n}/m_{1})\bmod1\approx(X_{n}/m_{1}-Y_{n}/m_{2})\bmod1=U_{n}$ -\end_inset - -. - The difference is at most -\begin_inset Formula $|Y_{n}/m_{1}-Y_{n}/m_{2}|=Y_{n}\left|\frac{1}{2^{31}-1}-\frac{1}{2^{31}-249}\right|=Y_{n}\frac{248}{(2^{31}-1)(2^{31}-249)}<\frac{248}{2^{31}-1}<2^{-23}$ -\end_inset - -. -\end_layout - -\begin_layout Enumerate -We have -\begin_inset Formula $mU_{0}=(X_{0}m/m_{1}-Y_{0}m/m_{2})\bmod m=(X_{0}m_{2}-Y_{0}m_{1})\bmod m=W_{0}$ -\end_inset - -, - and also -\begin_inset Formula -\begin{multline*} -U_{n+1}=(aX_{n}\bmod m_{1}/m_{1}-aY_{n}\bmod m_{2}/m_{2})\bmod1=\\ -=a(X_{n}/m_{1}-Y_{n}/m_{2})\bmod1=aU_{n}\bmod1, -\end{multline*} - -\end_inset - -so by induction -\begin_inset Formula $W_{n}\equiv mU_{n}$ -\end_inset - -. -\end_layout - -\end_body -\end_document |
