Proof: Add Four

Let's prove the following theorem:

((a + a) + a) + a = a4

Proof:

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Proof Table
# Claim Reason
1 (a + a) + a = a3 (a + a) + a = a3
2 ((a + a) + a) + a = (a3) + a if (a + a) + a = a3, then ((a + a) + a) + a = (a3) + a
3 a = a1 a = a1
4 (a3) + a = (a3) + (a1) if a = a1, then (a3) + a = (a3) + (a1)
5 (a3) + (a1) = a ⋅ (3 + 1) (a3) + (a1) = a ⋅ (3 + 1)
6 3 + 1 = 4 3 + 1 = 4
7 a ⋅ (3 + 1) = a4 if 3 + 1 = 4, then a ⋅ (3 + 1) = a4
8 (a3) + (a1) = a4 if (a3) + (a1) = a ⋅ (3 + 1) and a ⋅ (3 + 1) = a4, then (a3) + (a1) = a4
9 (a3) + a = a4 if (a3) + a = (a3) + (a1) and (a3) + (a1) = a4, then (a3) + a = a4
10 ((a + a) + a) + a = a4 if ((a + a) + a) + a = (a3) + a and (a3) + a = a4, then ((a + a) + a) + a = a4
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