Function assert_inferred_belief 

pub fn assert_inferred_belief(
    agent_did: u64,
    proposition_hash: u64,
    source_hash: u64,
    ts: u64,
) -> [NQuin; 3]

Record that agent_did holds an InferredBelief about proposition_hash, derived from source_hash (an AgentQuery or HearsayEvent).

Returns 3 quins in agent_epistemic_context(agent_did):

1. agent_did → infersFrom → source_hash
2. agent_did → cog:believes → proposition_hash
3. proposition_hash → prov:wasDerivedFrom → source_hash