How is this statement correct?
We consider consistency model A stronger than model B when the first allows fewer histories.
Mentioned here: Consistency Models - Distributed Systems for Practitioners (educative.io)
Hi @Ashwini_Jha !!
The statement “We consider consistency model A stronger than model B when the first allows fewer histories” is correct.
In the context of consistency models, the term “histories” refers to the possible sequences of operations and events that can occur in a distributed system. Each operation in a distributed system (e.g., read or write) is associated with a timestamp or order, and the sequence of these operations creates a history.
When we say that consistency model A is stronger than consistency model B, it means that model A imposes more restrictions or makes more assumptions about the possible behaviors of the system compared to model B. In other words, model A is more stringent in defining what types of histories are considered valid or allowed in the system.
With a stronger consistency model, there are fewer permissible sequences of operations or histories. This implies that the system’s behavior is more predictable and that it provides stronger guarantees about the ordering and visibility of operations.
On the other hand, a weaker consistency model allows for more flexible behavior and a wider range of possible histories, which might result in looser guarantees about the ordering and visibility of operations.
To summarize, the strength of a consistency model is determined by the set of histories it allows. A stronger consistency model permits fewer histories and provides more guarantees, while a weaker consistency model permits a broader range of histories and offers more relaxed guarantees.
I hope it helps. Happy Learning 
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