epelling interaction). In this case, for all $u$, the critical value of the interaction parameter $w$ is equal to $w_c(u,t=1)=1$. This means that the chains can not be segregated, even for extremely small attraction between them. For both fractals $b=2$ and $b=3$, the fixed points that pertain to the critical value $w_c$, for $u\neq u_\theta$, are the same as for $0<t<1$. For $u=u_\theta$ the symmetrical fixed point is reached, $(A_\theta,B_\theta,C^*,A_\theta
C^*,A_\theta C^*,A_\theta C^*,A_\theta C^*,B_\theta C^*,B_\theta
C^*)$, in contrast to the case $0<t<1$. Values of $A_\theta=A^*$, $B_\theta=B^*$ and $C^*$ can be found in the middle part of the table \[tab:CSAWs\], while the values of the contact critical exponents are $\varphi(b=2)=0.6102$, and $\varphi(b=3)=0.5907$.

Finally, one should mention that recently, using the Monte Carlo renormalization group (MCRG) method, the contact exponent $\varphi$ was calculated for $b$ up to 40, for the case when the intra-chain interactions within the 3D chain are negligible, $u\to
0$ [@ZivicJSTAT]. Comparing the reported MCRG data $\varphi^{MC}(b=2)=0.5440\pm0.0056$ and $\varphi^{MC}(b=3)=0.4969\pm0.0024$ with our exact findings $\varphi(b=2)=0.5428$ and $\varphi(b=3)=0.4973$, we can see that MCRG data are in excellent agreement with our exact findings. In [@ZivicJSTAT] it was also demonstrated that $\varphi^{MC}$, as a function of the scaling parameter $b$, continues decreasing with increasing $b$, and, it seems that in the fractal-to-Euclidean crossover region (*i.e.* in the limit $b\to\infty$) it goes to the proposed zero Euclidean value. The inequality $\varphi(b=2)>\varphi(b=3)$ is satisfied not only for weak intra-chain interactions ($u<u_\theta$), but also for $u\geq
u_\theta$, as can be seen in table \[tab:CSAWs\]. Unfortunately, in the range $u\geq u_\theta$, the MCRG calculation of $\varphi$ is not feasible, so that prediction for the large $b$ behavior of $\varphi(u\geq u_\theta)$, only on the bases of our exact data, is not possible.

Summary and conclus