14 lines
440 B
Text
14 lines
440 B
Text
import logic
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open bool eq.ops tactic eq
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variables a b c : bool
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axiom H1 : a = b
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axiom H2 : b = c
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check have e1 [visible] : a = b, from H1,
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have e2 : a = c, by apply trans; apply e1; apply H2,
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have e3 : c = a, from e2⁻¹,
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have e4 [visible] : b = a, from e1⁻¹,
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have e5 : b = c, from e4 ⬝ e2,
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have e6 : a = a, from H1 ⬝ H2 ⬝ H2⁻¹ ⬝ H1⁻¹ ⬝ H1 ⬝ H2 ⬝ H2⁻¹ ⬝ H1⁻¹,
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e3 ⬝ e2
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