# Question about multi agent linked to the same policy

**URL:** <https://discuss.ray.io/t/question-about-multi-agent-linked-to-the-same-policy/3744>\
**Category:** RLlib\
**Created:** [October 7, 2021, 11:52am UTC](https://discuss.ray.io/t/question-about-multi-agent-linked-to-the-same-policy/3744 "2021-10-07T11:52:27Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![carlorop](https://avatars.discourse-cdn.com/v4/letter/c/b19c9b/32.png) [@carlorop](https://discuss.ray.io/u/carlorop)\
**Post date:** [October 7, 2021, 11:52am UTC](https://discuss.ray.io/t/question-about-multi-agent-linked-to-the-same-policy/3744/1 "2021-10-07T11:52:27Z")

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I am using different agents, some of them are linked to the same policy using _“policy\_mapping\_fn”_. In such a case, would these agents behave as the same agent (sharing parameters and experience buffer) or would they be different agents with different parameters that predict using the same algorithm?. In the latter case, would the buffer of experiences be shared or would each agent have its own buffer?

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**Author:** ![mannyv](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ray.io/mannyv/32/606_2.png) [@mannyv](https://discuss.ray.io/u/mannyv)\
**Post date:** [October 7, 2021, 12:19pm UTC](https://discuss.ray.io/t/question-about-multi-agent-linked-to-the-same-policy/3744/2 "2021-10-07T12:19:10Z")

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Hi @carlorop,

The short answer is that agents that map to the same policy use the same models and buffer.

Here is a slightly more involved answer:

> [@Adding virtual agents in MARL](https://discuss.ray.io/t/adding-virtual-agents-in-marl/3708/2):
>
> Hi @Aceticia, Your idea is good. Any number of agents can share the same policy. Each will use the policy independently during execution (sampling rollouts). During training if you do not add any centralizing peices like for example the centralized critic, or an algorithm like qmix or maddpg then each transition is considered separately for each agent. During the actual loss calculations, the losses are computed in separate batches based on policy not agent. So if you have 3 agents that all m…

Does it make sense?