Search for: [Abstract = "We consider a two\-phase Hele\-Shaw cell whether or not the gap thickness is time\-dependent. We construct an exact solution in terms of the Schwarz function of the interface for the two\-phase Hele\-Shaw flow. The derivation is based upon the single\-valued complex velocity potential instead of the multiple\-valued complex potential. As a result, the construction is applicable to the case of the time\-dependent gap. In addition, there is no need to introduce branch cuts in the computational domain. Furthermore, the interface evolution in a two\-phase problem is closely linked to its counterpart in a one\-phase problem."]