f5fd962a25
Summary: - Adds configuration option `exponentiation.threshold` - An expression `b^n` where `b` and `n` are literals is not reduced by `whnf`, `simp`, and `isDefEq` if `n > exponentiation.threshold`. Motivation: prevents system from becoming irresponsive and/or crashing without memory. TODO: improve support in the kernel. It is using a hard-coded limit for now.
47 lines
1.2 KiB
Text
47 lines
1.2 KiB
Text
/--
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warning: exponent 10000000 exceeds the threshold 256, exponentiation operation was not evaluated, use `set_option exponentiation.threshold <num>` to set a new threshold
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---
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error: maximum recursion depth has been reached
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use `set_option maxRecDepth <num>` to increase limit
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use `set_option diagnostics true` to get diagnostic information
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-/
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#guard_msgs in
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example : 2^2^8000000 = 3^3^10000000 :=
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rfl
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/--
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-/
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#guard_msgs in
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set_option exponentiation.threshold 258 in
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example : 2^257 = 2*2^256 :=
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rfl
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/--
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warning: exponent 2008 exceeds the threshold 256, exponentiation operation was not evaluated, use `set_option exponentiation.threshold <num>` to set a new threshold
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---
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warning: declaration uses 'sorry'
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---
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error: (kernel) deep recursion detected
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---
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info: k : Nat
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h : k = 2008 ^ 2 + 2 ^ 2008
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⊢ ((4032064 + 2 ^ 2008) ^ 2 + 2 ^ (4032064 + 2 ^ 2008)) % 10 = 6
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-/
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#guard_msgs in
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example (k : Nat) (h : k = 2008^2 + 2^2008) : (k^2 + 2^k)%10 = 6 := by
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simp [h]
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trace_state
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sorry
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/--
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warning: declaration uses 'sorry'
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---
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info: k : Nat
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h : k = 2008 ^ 2 + 2 ^ 2008
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⊢ ((2008 ^ 2 + 2 ^ 2008) ^ 2 + 2 ^ (2008 ^ 2 + 2 ^ 2008)) % 10 = 6
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-/
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#guard_msgs in
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example (k : Nat) (h : k = 2008^2 + 2^2008) : (k^2 + 2^k)%10 = 6 := by
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rw [h]
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trace_state
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sorry
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