Question Number 186285 by Shrinava last updated on 03/Feb/23
$$\mathrm{Prove}\:\mathrm{that}: \\ $$$$\mathrm{R}\:\left(\mathrm{m}\:,\:\mathrm{n}\right)\:\leqslant\:\mathrm{C}_{\boldsymbol{\mathrm{m}}+\boldsymbol{\mathrm{n}}} ^{\boldsymbol{\mathrm{m}}} \\ $$$$\mathrm{Here}\:\:\mathrm{R}\:\:\mathrm{states}\:\mathrm{the}\:\:\mathrm{Ramsey}\:\:\mathrm{theory} \\ $$
Commented by mr W last updated on 03/Feb/23
$${R}\left({m},{n}\right)\leqslant{R}\left({m}−\mathrm{1},{n}\right)+{R}\left({m},{n}−\mathrm{1}\right) \\ $$$${R}\left({m},{n}\right)\leqslant\begin{pmatrix}{{m}+{n}−\mathrm{2}}\\{{m}−\mathrm{1}}\end{pmatrix} \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:=\begin{pmatrix}{{n}+{m}−\mathrm{1}}\\{{m}}\end{pmatrix}−\begin{pmatrix}{{n}+{m}−\mathrm{2}}\\{{m}}\end{pmatrix} \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:=\begin{pmatrix}{{n}+{m}}\\{{m}}\end{pmatrix}−\begin{pmatrix}{{n}+{m}−\mathrm{1}}\\{{m}−\mathrm{1}}\end{pmatrix}−\begin{pmatrix}{{n}+{m}−\mathrm{2}}\\{{m}}\end{pmatrix} \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\leqslant\begin{pmatrix}{{n}+{m}}\\{{m}}\end{pmatrix} \\ $$
Commented by Shrinava last updated on 03/Feb/23
$$\mathrm{perfect}\:\mathrm{dear}\:\mathrm{professor}\:\mathrm{thank}\:\mathrm{you}\:\mathrm{so}\:\mathrm{much} \\ $$