prologues:=2; 
beginfig(1);
u:=0.025cm;
pickup pencircle scaled 1;
pair origin,top_left,bottom_right;
origin=(320u,860u);
top_left=(320u,1060u);
bottom_right=(580u,860u);
path vert_axis,horiz_axis,budget_set;
vert_axis=origin--top_left;
draw vert_axis;
label.lft(btex Alice etex,top_left);
label.bot(btex Bob etex,bottom_right);
label.llft(btex $0$ etex,origin);
horiz_axis= origin--bottom_right;
draw horiz_axis;
pair ulbl,brbl;
ulbl=7/8[origin,top_left];
brbl=3/4[origin,bottom_right];
pair top_right,int,rbar;
top_right=whatever[brbl,brbl+(ulbl-origin)]=whatever[ulbl,ulbl+(brbl-origin)];
int=(1/5)[origin,ulbl];
rbar=whatever[int,((7/8)[brbl,top_right])]=whatever[ulbl,top_right];
pickup pencircle scaled 2;
draw int--rbar;
label.lft(btex $x^\ast_a(0)$ etex, int);
pair intb,rb;
intb=(1/4)[origin,brbl];
rb=whatever[intb,((15/16)[ulbl,top_right])]=whatever[int,rbar];
pickup pencircle scaled 1;
draw intb--((15/16)[ulbl,top_right]);
label.bot(btex $x^\ast_b(0) $ etex,intb);
pair xee,xeb,xea;
xee=whatever[int,rbar]=whatever[intb,((15/16)[ulbl,top_right])];
xeb=whatever[xee,xee+(origin-ulbl)]=whatever[origin,bottom_right];
xea=whatever[xee,xee+(origin-brbl)]=whatever[origin,top_left];
draw xee--xea dashed evenly scaled 1;
draw xee--xeb dashed evenly scaled 1;
label.bot(btex $x^e_b$ etex,xeb);
label.lft(btex $x^\ast(x^e_b)$ etex,xea);
endfig;
end