  To describe two-place physical problems, many possible models named Alice-Bob
(AB) systems are proposed. To find and to solve these systems, the Parity (P),
time reversal (T), charge conjugation (C), shifted-parity ($P_s$, parity with a
shift), delayed time reversal ($T_d$, time reversal with a delay) and their
possible combinations such as PT, PC, $P_sC$, $P_sT_d$ and $P_sT_dC$ etc. can
be successively used. Especially, some special types of $P_s$-$T_d$-$C$ group
invariant multi-soliton solutions for the KdV-KP-Toda type, mKdV-sG type, NLS
type and discrete $H_1$ type AB systems are explicitly constructed.
