 A group presentation (∗) as above is said to satisfy the T("q") "small cancellation condition" if whenever 3 ≤ t 1...,"r"t in "R" are such that "r"1 ≠ "r"2−1..., 
"r"t ≠ "r"1−1 then at least one of the products "r"1"r"2...,"r"t−1"r"t, "r"t"r"1 is freely reduced as written.Geometrically, condition T("q") essentially means that if "D" is a reduced van Kampen diagram over (∗) then every interior vertex of "D" of degree at least three actually has degree at least "q".The main result regarding the metric small cancellation condition is the following statement (see Theorem 4.4 in Ch.