The main algorithm Formula computes .  Subroutine computes a suitable origin for .  Subroutine Plan determines a proper sequence of shift operators and inverse shift operators which should be applied to to produce . 

proc Formula
:=
:=
:=
:=
Delete elements and have in common. 
Delete elements and have in common. 
:=;
:=;
for bucket in plan do
:=;
if then
for from 1 to do
:=
;
od;
elif then
for from to do
:=
;
od;
fi;
od;
return ;