We define two functions f and g on the unit interval [0, 1] to be strongly conjugate $\operatorname {iff}$ there is an order-preserving homeomorphism h of [0, 1] such that g = h -1 fh (a minor ...

Dorte Kronborg, Peter Aaby, Piecewise Comparison of Survival Functions in Stratified Proportional Hazards Models, Biometrics, Vol. 46, No. 2 (Jun., 1990), pp. 375-380 ...