25 lines
630 B
Python
25 lines
630 B
Python
class Proposition:
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def __init__(self, text):
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self.text = text
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def __call__(self, propositions):
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"""Is true given propositions."""
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return None
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def __bool__(self):
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"""Is true in itself."""
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return None
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def __inv__(self):
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"""Is negation true in itself."""
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return not self
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class Axiom(Proposition):
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def __init__(self, text):
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self.text = text
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def __call__(self, propositions):
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return True
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def __bool__(self):
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return True
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class Extensionality(Axiom):
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def __init__(self):
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self.text = "∀x∀y(∀z(z∈x⇔z∈y))"
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