In this note, necessary and sufficient conditions are given for the in
tersection of the m(-1) simplex co{xi(1),...,xi(m)} of m affinely inde
pendent vectors xi(1),...,xi(m) of R(n) and the negative orthant R-(n)
to be empty, i.e., co{xi(1),...,xi(m)} boolean AND R-(n)=<empty set>,
where m less than or equal to n. It is also shown that the special ca
se m=2 can be checked easily. These results suggest that the above-men
tioned emptiness can be checked recursively. Some numerical examples a
re given to illustrate the results. Potential applications of these re
sults include the compatible multicommodity flow problems and satisfic
ing solution problems.