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Concurrent Systems/notes/9 - Consensus.md

@@ -36,4 +36,16 @@ Universality of consensus holds as folows:
 - create a total order on the operations O, by using consensus objects
 - force all processes to follow this order to locally simulate O
 	- all local copies are consistent
+(O can be any object, e.g. a queue)
+
+### First attempt (non wait-free)
+Let us first concentrate on obj's with deterministic specifications (we will see how to handle non-determinism later on)
+
+Process $p_i$ wants to invoke operation op of object Z with arguments args, locally runs:
+```
+result_i <- ⊥
+invoc_i <- ⟨op(args) , i⟩
+wait result_i != ⊥
+return result_i
+```