Compfiles/Imo1986P5.lean
8 declarations, 0 contain sorry, 0 declared as axioms
International Mathematical Olympiad 1986, Problem 5
Find all functions f, defined on the non-negative real numbers and taking nonnegative real values,
such that:
- $f(xf(y))f(y) = f(x + y)$ for all $x, y \ge 0$,
- $f(2) = 0$,
- $f(x) \ne 0$ for $0 \le x < 2$.
Imports (2)
Imported by 1 file
- structure
Imo1986P5.IsGoodline 35 sourcestandard axioms: Classical.choice, Quot.sound, propext what this means
Statement uses:
NNReal - theorem
Imo1986P5.IsGood.map_addline 55 sourcestandard axioms: Classical.choice, Quot.sound, propext what this means
Statement uses:
NNReal, Imo1986P5.IsGood,Eq,HAdd.hAdd,HMul.hMulProof uses:
Eq.symm,Imo1986P5.IsGood.map_add_rev12 instances, coercions and auxiliary constants left out.
- theorem
Imo1986P5.IsGood.map_eq_zeroline 58 sourcestandard axioms: Classical.choice, Quot.sound, propext what this means
Statement uses:
NNReal, Imo1986P5.IsGood,Iff,Eq,OfNat.ofNat,LE.le,NatProof uses:
Iff.intro,Iff.mp,Not,LT.lt,not_lt,Imo1986P5.IsGood.map_ne_zero,HAdd.hAdd,Exists,ExistsAddOfLE.exists_add_of_le,Eq.mpr,id,congrArg,add_comm,HMul.hMul, Imo1986P5.IsGood.map_add,Imo1986P5.IsGood.map_two,MulZeroClass.mul_zero,Eq.refl,Eq.symm47 instances, coercions and auxiliary constants left out.
Tactic trace: 3 steps
Open to load the checked before-and-after goal states.
- theorem
Imo1986P5.IsGood.map_ne_zero_iffline 63 sourcestandard axioms: Classical.choice, Quot.sound, propext what this means
Statement uses:
NNReal, Imo1986P5.IsGood,Iff,Ne,OfNat.ofNat,LT.lt,NatProof uses:
of_eq_true,Eq.trans,True,congrFun',congrArg,Not,Eq,LE.le,propext, Imo1986P5.IsGood.map_eq_zero,iff_self32 instances, coercions and auxiliary constants left out.
Tactic trace: 1 steps
Open to load the checked before-and-after goal states.
- theorem
Imo1986P5.IsGood.map_of_lt_twoline 65 sourcestandard axioms: Classical.choice, Quot.sound, propext what this means
Statement uses:
NNReal, Imo1986P5.IsGood,LT.lt,OfNat.ofNat,Nat,Eq,HDiv.hDiv,HSub.hSubProof uses:
tsub_pos_of_lt,Ne,Iff.mpr, Imo1986P5.IsGood.map_ne_zero_iff,le_antisymm,Eq.mpr,LE.le,HMul.hMul,id,congrArg,propext,le_div_iff₀,Eq.symm,le_div_iff₀',Ne.bot_lt,HAdd.hAdd,tsub_le_iff_right, Imo1986P5.IsGood.map_eq_zero, Imo1986P5.IsGood.map_add,div_mul_cancel₀and 12 more73 instances, coercions and auxiliary constants left out.
Tactic trace: 9 steps
Open to load the checked before-and-after goal states.
- theorem
Imo1986P5.IsGood.map_eqline 76 sourcestandard axioms: Classical.choice, Quot.sound, propext what this means
Statement uses:
NNReal, Imo1986P5.IsGood,Eq,HDiv.hDiv,OfNat.ofNat,Nat,HSub.hSubProof uses:
Or,LT.lt,LE.le,lt_or_ge, Imo1986P5.IsGood.map_of_lt_two,Eq.mpr,id,congrArg,tsub_eq_zero_of_le,div_zero,propext, Imo1986P5.IsGood.map_eq_zero51 instances, coercions and auxiliary constants left out.
Tactic trace: 1 steps
Open to load the checked before-and-after goal states.
- determine
Imo1986P5.SolutionSetline 84 sourcestandard axioms: Classical.choice, Quot.sound, propext what this means
Statement uses:
Set,NNRealProof uses:
Singleton.singleton,HDiv.hDiv,OfNat.ofNat,HSub.hSub12 instances, coercions and auxiliary constants left out.
- problem
Imo1986P5.imo1986_p5line 86 sourcestandard axioms: Classical.choice, Quot.sound, propext what this means
Statement uses:
NNReal,Iff, Imo1986P5.IsGood,Membership.mem,Set, Imo1986P5.SolutionSetProof uses:
Iff.intro,funext,HDiv.hDiv,OfNat.ofNat,HSub.hSub, Imo1986P5.IsGood.map_eq,Imo1986P5.IsGood.mk,LT.lt,Nat,LE.le,Or,Eq,lt_or_ge,HMul.hMul,HAdd.hAdd,Or.inl,Ne,LT.lt.ne',tsub_pos_of_lt,Eq.mprand 31 more99 instances, coercions and auxiliary constants left out.
Tactic trace: 15 steps
Open to load the checked before-and-after goal states.