theorem Th28: :: HURWITZ:28

for L being non empty non degenerated right_complementable almost_left_invertible well-unital distributive add-associative right_zeroed associative commutative doubleLoopStr
for p being Polynomial of L holds
( deg p = 1 iff ex x, z being Element of L st
( x <> 0. L & p = x * (rpoly (1,z)) ) )