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Shlomo Morant Self stabilizing protocols for distributed systems in the shared memory model are defined and studied. The protocols presented here improve upon previous protocols in two ways: Ftrst, it is assumed that the only atomic ol>erations are either read <r write ~ the shared memory. Second, our protocols work for dynamic networks, in which the topology of lhe network may change during the execution. Three dynamic self-stabilizing protocols are presented. The first protocol is a spanning tree protocol for systems with any connected communication graph. The second protocol is a mutual exclusion protocol for tree structured systems. The third protocol is a self stabilizing protocol for mutual exclusion, for systems with a general (connected) communication graph. This last protocol is obtained by combining the previous two protocols. The combination employs a simple technique called/air protocol composition. which is enabled by both the self-stability and by the flexibility of dynamic protocols. t Deparunent d. Computer Science, Technion -unel Instilute of Technology, Haifa 32000, ISRAEL. Pan of Ibis Rsearch wu supported in part by Technion V.P:R. FlD1ds Wellner Research Fund, and by the Foundation for Research in Electronics, ComputeTl and Communicatioos, adminiSlnled by the Isnel.Academy of Sciences and Humanities. t Department of Electrical Engineering, Technioo Israel Institute of Teclmology, Haifa 32000, ISRAEL. T ec hn io n C om pu te r Sc ie nc e D ep ar tm en t T eh ni ca l R ep or t C S0 59 0 19 89