20 lines
402 B
Text
20 lines
402 B
Text
constant p : nat → Prop
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constant q : nat → Prop
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constant h : nat → Prop
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axiom pq0 : q 0 → p 0
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axiom phx : ∀ x, h x → p x
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example (h₁ : h 1) : ∃ x, p x :=
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begin
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constructor,
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mapply pq0 <|> mapply phx, -- The first `mapply` should fail
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assumption
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end
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open nat
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example : ∃ x, succ 0 > x :=
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begin
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constructor,
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fail_if_success { mapply succ_lt_succ },
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apply zero_lt_succ
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end
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