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docs/MonadState.md

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+
+$$
+\text{State}(S,A)\simeq S \to A\times S\\
+\text{Branch}(S,A)\simeq S \to \mathcal P (A\times S)\\
+\text{Fork}(G,S,A)\simeq G\times S \to \mathcal P (A\times S) \times G^?
+$$
+State
+$$
+m_a \succ f = s_0 \mapsto m_b (s_1)\\
+(a,s_1)=m_a (s_0),\quad  m_b =f(a)
+$$
+Branch
+$$
+m_a \succ f = s_0 \mapsto \text{interleave} \{ m_b(s_1)\ | \ (a,s_1) \in m_a(s_0), m_b = f(a)\}
+$$
+Fork
+$$
+m_a \succ f = s_0 \mapsto 
+$$