clf;
subplot(231)
plot(3,3,'r+','MarkerSize',12);
grid on;
axis([0 9 0 9]);
set(gca,'ytick',[0 1 2 3 4 5 6 7 8 9]);
set(gca,'xtick',[0 1 2 3 4 5 6 7 8 9]);
title('instance #1');
subplot(232)
plot(3,3,'r+',5,5,'r+','MarkerSize',12);
% You can plot a rectangle with the command rectangle
% see help rectangle
hold on;
r=rectangle('Position',[2 2 4 5],'LineWidth',3,'EdgeColor','g');
grid on;
title('instance #2');
axis([0 9 0 9]);
set(gca,'ytick',[0 1 2 3 4 5 6 7 8 9]);
set(gca,'xtick',[0 1 2 3 4 5 6 7 8 9]);
subplot(233)
h=plot(3,3,'r+',5,5,'r+',1,2,'bo','MarkerSize',12);
title('instance #3');
grid on;
axis([0 9 0 9]);
set(gca,'ytick',[0 1 2 3 4 5 6 7 8 9]);
set(gca,'xtick',[0 1 2 3 4 5 6 7 8 9]);
subplot(234)
plot(3,3,'r+',5,5,'r+',1,2,'bo',4,8,'bo','MarkerSize',12);
title('instance #4');
grid on;
axis([0 9 0 9]);
set(gca,'ytick',[0 1 2 3 4 5 6 7 8 9]);
set(gca,'xtick',[0 1 2 3 4 5 6 7 8 9]);
subplot(235)
plot(3,3,'r+',5,5,'r+',1,2,'bo',4,8,'bo',7,2,'r+','MarkerSize',12);
title('instance #5');
grid on;
axis([0 9 0 9]);
set(gca,'ytick',[0 1 2 3 4 5 6 7 8 9]);
set(gca,'xtick',[0 1 2 3 4 5 6 7 8 9]);
subplot(236)
plot(3,3,'r+',5,5,'r+',1,2,'bo',4,8,'bo',7,2,'r+',8,5,'bo','MarkerSize',12);
title('instance #6');
grid on;
axis([0 9 0 9]);
set(gca,'ytick',[0 1 2 3 4 5 6 7 8 9]);
set(gca,'xtick',[0 1 2 3 4 5 6 7 8 9]);