===== Step function integral =====
==== Set ====
| @#55CCEE: context     | @#55CCEE: $\langle X,\Sigma,\mu\rangle\in \mathrm{MeasureSpace}(X)$ |

| @#55EE55: postulate   | @#55EE55: $\int_X:\mathcal T^+\to \mathbb R_+$ |

| $ f\equiv \sum_{j=1}^n\alpha_j\cdot\chi_{E_n} \in \mathcal T^+$ |

| @#55EE55: postulate   | @#55EE55: $\int_X\ f\ \mathrm d\mu:=\sum_{j=1}^n\alpha_j\cdot\mu(E_n) $ |

==== Discussion ====
=== Reference ===
==== Parents ====
=== Context ===
[[Positive real step function]], 
[[Characteristic function]],
[[Finite sum of complex numbers]]