\psset{unit=0.5cm}
%
\pspicture(-16,-3.5)(4,11)
%\showgrid
% The encircling:
\psline[linewidth=0.4,linecolor=lightgray,linearc=0.6](-16,3)(0,3)
\pspolygon[linewidth=0.4,linecolor=lightgray,linearc=0.6](-16,9)(0,9)(0,-2)(-16,-2)(-16,9)
% The text for the encircling
\rput[l](1,6){{\tiny Coloured points}}
\rput[l](1,5.3){{\tiny are arranged}}
\rput[l](1,4.6){{\tiny on this ``circle''.}}
% The arrow
\psline[linecolor=gray,linewidth=0.2]{->}(3.5,4.2)(0,1.5)
% upper green
\psline[linewidth=0.1,linecolor=gray](-1,7)(-1,9)
\pscircle[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-1,9){0.35}
\rput(-1,9){
\pspolygon[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-0.3,0.5)(-0,1)(0.3,0.5)(-0.3,0.5)
}
% upper red
\psline[linewidth=0.1,linecolor=gray](-2,7)(-2,9)
\pscircle[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-2,9){0.35}
\rput(-2,9){
\pspolygon[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-0.3,1)(-0,0.5)(0.3,1)(-0.3,1)
}
% upper green
\psline[linewidth=0.1,linecolor=gray](-5,7)(-5,9)
\pscircle[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-5,9){0.35}
\rput(-5,9){
\pspolygon[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-0.3,0.5)(-0,1)(0.3,0.5)(-0.3,0.5)
}
% upper red
\psline[linewidth=0.1,linecolor=gray](-7,7)(-7,9)
\pscircle[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-7,9){0.35}
\rput(-7,9){
\pspolygon[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-0.3,1)(-0,0.5)(0.3,1)(-0.3,1)
}
% upper green
\psline[linewidth=0.1,linecolor=gray](-8,7)(-8,9)
\pscircle[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-8,9){0.35}
\rput(-8,9){
\pspolygon[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-0.3,0.5)(-0,1)(0.3,0.5)(-0.3,0.5)
}
% upper red
\psline[linewidth=0.1,linecolor=gray](-9,7)(-9,9)
\pscircle[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-9,9){0.35}
\rput(-9,9){
\pspolygon[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-0.3,1)(-0,0.5)(0.3,1)(-0.3,1)
}
% upper green
\psline[linewidth=0.1,linecolor=gray](-11,7)(-11,9)
\pscircle[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-11,9){0.35}
\rput(-11,9){
\pspolygon[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-0.3,0.5)(-0,1)(0.3,0.5)(-0.3,0.5)
}
% upper red
\psline[linewidth=0.1,linecolor=gray](-14,7)(-14,9)
\pscircle[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-14,9){0.35}
\rput(-14,9){
\pspolygon[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-0.3,1)(-0,0.5)(0.3,1)(-0.3,1)
}
% lower red
\psline[linewidth=0.1,linecolor=gray](-15,-2)(-15,0)
\pscircle[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-15,-2){0.35}
\rput(-15,-2){
\pspolygon[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-0.3,-0.5)(-0,-1)(0.3,-0.5)(-0.3,-0.5)
}
% lower green
\psline[linewidth=0.1,linecolor=gray](-12,-2)(-12,0)
\pscircle[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-12,-2){0.35}
\rput(-12,-2){
\pspolygon[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-0.3,-1)(-0,-0.5)(0.3,-1)(-0.3,-1)
}
% lower red
\psline[linewidth=0.1,linecolor=gray](-11,-2)(-11,0)
\pscircle[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-11,-2){0.35}
\rput(-11,-2){
\pspolygon[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-0.3,-0.5)(-0,-1)(0.3,-0.5)(-0.3,-0.5)
}
% lower green
\psline[linewidth=0.1,linecolor=gray](-10,-2)(-10,0)
\pscircle[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-10,-2){0.35}
\rput(-10,-2){
\pspolygon[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-0.3,-1)(-0,-0.5)(0.3,-1)(-0.3,-1)
}
% lower red
\psline[linewidth=0.1,linecolor=gray](-9,-2)(-9,0)
\pscircle[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-9,-2){0.35}
\rput(-9,-2){
\pspolygon[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-0.3,-0.5)(-0,-1)(0.3,-0.5)(-0.3,-0.5)
}
% lower green
\psline[linewidth=0.1,linecolor=gray](-7,-2)(-7,0)
\pscircle[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-7,-2){0.35}
\rput(-7,-2){
\pspolygon[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-0.3,-1)(-0,-0.5)(0.3,-1)(-0.3,-1)
}
% lower red
\psline[linewidth=0.1,linecolor=gray](-6,-2)(-6,0)
\pscircle[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-6,-2){0.35}
\rput(-6,-2){
\pspolygon[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-0.3,-0.5)(-0,-1)(0.3,-0.5)(-0.3,-0.5)
}
% lower green
\psline[linewidth=0.1,linecolor=gray](-5,-2)(-5,0)
\pscircle[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-5,-2){0.35}
\rput(-5,-2){
\pspolygon[linewidth=0.1,linecolor=black,fillcolor=white,fillstyle=solid](-0.3,-1)(-0,-0.5)(0.3,-1)(-0.3,-1)
}
%%% The lattice paths
%% The square grid with labels
\lightgridlinestyle
% The vertical lines:
\setcounter{dummycount}{-7}
\multido{\nx=-15+1}{15}{
	\psline(\nx,0)(\nx,7)
	\rput(\nx,-1){${\scriptscriptstyle\arabic{dummycount}}$}
	\stepcounter{dummycount}
}
% The horizontal lines:
\multido{\nx=0+1}{8}{	\psline(-15,\nx)(-1,\nx)}
% The recolouring paths
\psset{linecolor=gray,linewidth=0.4,linearc=0.6}
\psline(-1,7)(-1,6)(-2,6)(-2,5)(-4,5)(-4,7)(-2,7)
\psline(-5,0)(-4,0)(-4,5)(-5,5)(-5,7)
\psline(-7,0)(-7,2)(-6,2)(-6,0)
\psline(-8,7)(-7,7)
\psline(-9,7)(-9,6)(-8,6)(-8,5)(-7,5)(-7,4)(-8,4)(-8,5)(-9,5)(-9,6)(-10,6)(-10,4)(-9,4)(-9,0)
\psline(-10,0)(-10,3)(-11,3)(-11,7)
\psline(-11,0)(-11,2)(-12,2)(-12,3)(-13,3)(-13,2)(-12,2)(-12,0)
\psline(-15,0)(-15,7)(-14,7)
% The lattice paths corresponding to T1
% Lattice paths:
\greenlinestyle
% Path 1:
\psline(-5.1,0.1)(-4.1,0.1)(-4.1,5.1)(-3.1,5.1)(-2.1,5.1)(-2.1,6.1)(-1.1,6.1)(-1.1,7.1)
% Path 2:
\psline(-7.1,0.1)(-7.1,2.1)(-6.1,2.1)(-5.1,2.1)(-5.1,7.1)
% Path 3:
\psline(-8.1,0.1)(-8.1,5.1)(-7.1,5.1)(-7.1,6.1)(-6.1,6.1)(-6.1,7.1)
% Path 4:
\psline(-10.1,0.1)(-10.1,4.1)(-9.1,4.1)(-9.1,6.1)(-8.1,6.1)(-8.1,7.1)
% Path 5:
\psline(-12.1,0.1)(-12.1,2.1)(-11.1,2.1)(-11.1,7.1)
% Path 6:
\psline(-13.1,0.1)(-13.1,3.1)(-12.1,3.1)(-12.1,7.1)
% Path 7:
\psline(-14.1,0.1)(-14.1,4.1)(-13.1,4.1)(-13.1,7.1)
% Starting/ending point
\greencirclestyle
\pscircle(-5.1,0.1){0.3}
\pscircle(-7.1,0.1){0.3}
\pscircle(-8.1,0.1){0.3}
\pscircle(-10.1,0.1){0.3}
\pscircle(-12.1,0.1){0.3}
\pscircle(-13.1,0.1){0.3}
\pscircle(-14.1,0.1){0.3}
\pscircle(-1.1,7.1){0.3}
\pscircle(-5.1,7.1){0.3}
\pscircle(-6.1,7.1){0.3}
\pscircle(-8.1,7.1){0.3}
\pscircle(-11.1,7.1){0.3}
\pscircle(-12.1,7.1){0.3}
\pscircle(-13.1,7.1){0.3}
% The lattice paths corresponding to T2
% Lattice paths:
\redlinestyle
% Path 1:
\psline[linewidth=0.15,linecolor=red](-5.9,-0.1)(-5.9,4.9)(-4.9,4.9)(-3.9,4.9)(-3.9,6.9)(-2.9,6.9)(-1.9,6.9)
% Path 2:
\psline[linewidth=0.15,linecolor=red](-7.9,-0.1)(-7.9,3.9)(-6.9,3.9)(-6.9,5.9)(-5.9,5.9)(-5.9,6.9)
% Path 3:
\psline[linewidth=0.15,linecolor=red](-8.9,-0.1)(-8.9,4.9)(-7.9,4.9)(-7.9,6.9)(-6.9,6.9)
% Path 4:
\psline[linewidth=0.15,linecolor=red](-10.9,-0.1)(-10.9,2.9)(-9.9,2.9)(-9.9,5.9)(-8.9,5.9)(-8.9,6.9)
% Path 5:
\psline[linewidth=0.15,linecolor=red](-12.9,-0.1)(-12.9,1.9)(-11.9,1.9)(-11.9,6.9)
% Path 6:
\psline[linewidth=0.15,linecolor=red](-13.9,-0.1)(-13.9,5.9)(-12.9,5.9)(-12.9,6.9)
% Path 7:
\psline[linewidth=0.15,linecolor=red](-14.9,-0.1)(-14.9,6.9)(-13.9,6.9)
\psset{linewidth=0.15,linecolor=red,linestyle=solid}
% Starting/ending point
\redcirclestyle
\pscircle(-5.9,-0.1){0.3}
\pscircle(-7.9,-0.1){0.3}
\pscircle(-8.9,-0.1){0.3}
\pscircle(-10.9,-0.1){0.3}
\pscircle(-12.9,-0.1){0.3}
\pscircle(-13.9,-0.1){0.3}
\pscircle(-14.9,-0.1){0.3}
\pscircle(-1.9,6.9){0.3}
\pscircle(-5.9,6.9){0.3}
\pscircle(-6.9,6.9){0.3}
\pscircle(-8.9,6.9){0.3}
\pscircle(-11.9,6.9){0.3}
\pscircle(-12.9,6.9){0.3}
\pscircle(-13.9,6.9){0.3}
%
\endpspicture