---

       # MATH introduce addition
[hear] (intro +);

[hear] (= (unary 1 1 1 0) / + (unary 1 1 1 0) (unary 0));

[hear] (= (unary 1 1 1 1 1 0) / + (unary 1 0) (unary 1 1 1 1 0));

[hear] (= (unary 1 1 1 1 1 0) / + (unary 1 0) (unary 1 1 1 1 0));

[hear] (= (unary 1 0) / + (unary 0) (unary 1 0));

[hear] (= (unary 1 1 1 1 1 1 0) / + (unary 1 1 1 1 0) (unary 1 1 0));

[hear] (= (unary 1 1 0) / + (unary 1 1 0) (unary 0));

[hear] (= (unary 1 1 1 1 1 1 0) / + (unary 1 1 0) (unary 1 1 1 1 0));

[hear] (= (unary 1 1 1 1 1 1 0) / + (unary 1 1 0) (unary 1 1 1 1 0));

[hear] (= (unary 1 1 1 1 0) / + (unary 1 1 0) (unary 1 1 0));

[hear] (= (unary 1 1 1 1 1 0) / + (unary 1 0) (unary 1 1 1 1 0));