theorem :: SRINGS_5:64

for n being non zero Nat
for x being Element of Product (n,the_set_of_all_left_open_real_bounded_intervals) ex a, b being Element of REAL n st
for t being Element of REAL n holds
( t in x iff for i being Nat st i in Seg n holds
t . i in ].(a . i),(b . i).] )