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Diff — Exponentiation

Revision #3175 → #3703 · back to history

modifiedExponentiation (positive integer exponent)b8fc6a52cb1b
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mathlib.moduleMathlib.Algebra.Group.DefsMathlib.Algebra.Group.Monoid
note`Monoid.npow` is the canonical inductive definition of iterated multiplication on a monoid.`Monoid.npow` is the class field defining iterated multiplication on a monoid.
modifiedZeroth, negative, and fractional powers649819e3e1bf
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noteInteger powers via `zpowRec`/`DivInvMonoid.zpow`, and rational/real extensions via `Real.rpow`.`zpowRec`/`DivInvMonoid.zpow` cover integer powers and `Real.rpow` real ones.
modifiedArchimedes' law of exponents for powers of tencae51c3b8666
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noteMathlib has the general `pow_add` law; the Archimedes historical specialization to powers of ten is not stated separately.The generic `pow_add` law subsumes the historical powers-of-ten specialization.
modifiedCube of b09ec9b6ab322
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noteThere is no dedicated `cube` decl; one uses `a^3` directly.No dedicated `cube` decl; users write `a^3`.
modifiedInductive definition of positive integer exponentiation65bede8935e2
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mathlib.moduleMathlib.Algebra.Group.DefsMathlib.Algebra.Group.Monoid
note`Monoid.npow_zero` and `Monoid.npow_succ` provide the inductive base and step.`Monoid.npow_zero`/`Monoid.npow_succ` (class fields) give the inductive base/step.
modifiedZero to the power of zero822eb083404a
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noteMathlib follows the convention `0^0 = 1` via `pow_zero`.Mathlib adopts the convention `0^0 = 1` via `pow_zero`.
modifiedNegative exponents in a monoid2a6bf781248e
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mathlib.declZPow.zpowDivInvMonoid.zpow
mathlib.moduleMathlib.Algebra.Group.DefsMathlib.Algebra.Group.DivInvMonoid
note`DivInvMonoid.zpow` defines integer powers for invertible elements.`DivInvMonoid.zpow` (class field) defines integer powers for invertible elements.
modifiedAlternating sign of powers of -1d0fd6a7cd129
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note`neg_one_pow_eq_pow_mod_two` captures the alternation; related `Odd.neg_one_pow` etc.`neg_one_pow_eq_pow_mod_two` captures the alternation.
modifiedPowers of negative bases do not converge0dcae5e47f31
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noteNo dedicated non-convergence lemma for `b<-1` in Mathlib.No dedicated non-convergence lemma for `b<-1`.
modifiedPower functions3c4827f1b026
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noteThe terminology `power function` has no dedicated Mathlib decl.No dedicated `power function` decl.
modifiedEven and odd power functions89bd5c3f059d
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noteNo `evenPowerFunction`/`oddPowerFunction` family is defined.No `evenPowerFunction`/`oddPowerFunction` family.
modifiedn th root of a nonnegative real7e1cc4582dfe
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noteNth roots are realized as `x ^ (1/n : ℝ)` using `Real.rpow`.Nth roots are realized as `x ^ (1/n : ℝ)` via `Real.rpow`.
modifiedPrincipal value and multivaluedness for negative bases2dd8e4958762
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note`Real.rpow_def_of_neg` gives a specific principal-value formula for `x < 0` but does not develop the multivalued discussion.`Real.rpow_def_of_neg` gives a principal-value formula for `x < 0` but no multivalued discussion.
modifiedReal exponent via limit of rational exponents4b6e5be81529
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noteMathlib defines `Real.rpow` via `exp ∘ log` rather than as a limit of rational approximations, though continuity is proved.Mathlib uses `exp ∘ log` rather than the rational-limit construction, though continuity is proved.
modifiedExponential function (limit definition)c1eb40e25a6c
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note`Real.exp` is defined via the power series; the `(1+x/n)^n` limit form is proved equivalent via `Real.tendsto_one_add_div_pow_exp`.`Real.exp` uses the power series; the `(1+x/n)^n` limit form is proved equivalent via `Real.tendsto_one_add_div_pow_exp`.
modifiedEuler's numberc7fea11fa08c
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noteMathlib has no dedicated `Real.e` constant; Euler's number is `Real.exp 1`, with numerical bounds like `Real.exp_one_gt_two`.No dedicated `Real.e`; Euler's number is `Real.exp 1` with numerical bounds like `Real.exp_one_gt_two`.
modifiedPolar form of n th roots of a complex number83e88beba778
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noteMathlib has nth-root theory and `Complex.cpow` but no single decl in polar form.Mathlib has nth-root theory and `Complex.cpow`, but no polar-form decl.
modifiedn distinct n th roots of a complex numberf278491112b6
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note`IsPrimitiveRoot.card_nthRoots` gives that `nthRoots n a` has cardinality `n` (when a root exists).`IsPrimitiveRoot.card_nthRoots` gives that `nthRoots n a` has cardinality `n`.
modifiedPrincipal n th root29b0f5b00a47
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notePrincipal root is `z ^ (1/n : ℂ)` via `Complex.cpow`; no `principalNthRoot` decl.Principal root is `z ^ (1/n : ℂ)` via `Complex.cpow`; no dedicated `principalNthRoot`.
modifiedNo continuous n th root on all of Ca8e38b259330
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noteNo dedicated obstruction lemma; related discontinuity of `Complex.log` at 0 is known.No dedicated obstruction lemma.
modifiedn th roots via roots of unity27bdda34c05a
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noteMathlib relates nth roots to primitive roots, e.g. via `IsPrimitiveRoot.nthRoots_eq`.Mathlib relates nth roots to primitive roots via `IsPrimitiveRoot.nthRoots_eq`.
modifiedGeometric arrangement of roots of unityc7711f9e9334
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noteRoots of unity arise as `exp (2π i k / n)` via `Complex.isPrimitiveRoot_exp`; no specific 'regular polygon' lemma.Roots of unity arise as `exp (2π i k / n)`; no explicit 'regular polygon' lemma.
modifiedOther values of multivalued logarithm and exponentiation93a7085406d1
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noteMathlib uses principal values; no multivalued branch enumeration. Anchor tightened to disambiguate from other 'If' sentences in this section.Mathlib uses principal values; no multivalued branch enumeration.
modifiedNumber of values of z^w for rational wa13de209f360
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noteNo multivalued count lemma in Mathlib. Anchor tightened to disambiguate from other 'If' sentences in this section.No multivalued-count lemma in Mathlib.
modifiedAlgebraic base, rational exponent gives algebraic131a33a7d52a
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note`IsAlgebraic.pow` covers integer powers; the rational exponent case via nth roots is not given a single Mathlib lemma.`IsAlgebraic.pow` covers integer powers; the rational-exponent case via nth roots has no single lemma.
modifiedExponentiation in a monoid63e93d132c8f
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mathlib.moduleMathlib.Algebra.Group.DefsMathlib.Algebra.Group.Monoid
note`Monoid.npow` is monoid exponentiation.`Monoid.npow` (class field) is monoid exponentiation.
modifiedNegative integer exponent in a monoided7436404a32
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mathlib.declZPow.zpowDivInvMonoid.zpow
mathlib.moduleMathlib.Algebra.Group.DefsMathlib.Algebra.Group.DivInvMonoid
note`DivInvMonoid.zpow` extends to negative integer exponents.`DivInvMonoid.zpow` (class field) extends to negative integer exponents.
modifiedConjugation notation0b9804e7e594
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noteMathlib has `conj_pow` (and `Units.conj_pow`) but no `x^y` conjugation notation per se.Mathlib has `conj_pow` but no `x^y` conjugation notation.
modifiedMatrix power7ea7c89cd85c
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mathlib.moduleMathlib.Algebra.Group.DefsMathlib.Algebra.Group.Monoid
noteSquare matrices form a monoid, so `A^n` is given by `Monoid.npow`; many `Matrix.*_pow` lemmas exist.Square matrices are a monoid, so `A^n` is `Monoid.npow`; many `Matrix.*_pow` lemmas exist.
modifiedFinite field1c7b933b7c9d
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noteFinite fields are realised as `Field` with `Finite`; `GaloisField p n` is the canonical construction.`GaloisField p n` is the canonical finite field construction.
modifiedPrimitive element of a finite fieldebe7f86da493
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note`instIsCyclicUnitsOfFinite` shows the unit group of any finite integral domain (incl. finite fields) is cyclic, so a primitive element exists; no `primitiveElement` decl specific to finite fields.`instIsCyclicUnitsOfFinite` gives cyclicity of the unit group, so a primitive element exists; no dedicated decl.
modifiedGalois group of finite field extensionda5709b90598
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note`FiniteField.instIsCyclicAlgEquivOfFinite` proves the Galois group is cyclic; no single 'Gal = ⟨Frob⟩' decl was found.`FiniteField.instIsCyclicAlgEquivOfFinite` proves the Galois group is cyclic; no single 'Gal = ⟨Frob⟩' decl.
modifiedn th power of a setd8d72d0faa80
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noteIterated Cartesian power is realised via `Fin n → S` or `Set.pi`, but there is no `Set.npow` decl.Iterated Cartesian power is realised via `Fin n → S` or `Set.pi`; no `Set.npow` decl.
modifiedSet of functions notation S^Tf04130b2e79b
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noteMathlib uses `T → S` (the Pi type) for function sets; cardinal exponentiation `#S ^ #T` matches via `Cardinal.power_def`.Mathlib uses the Pi type `T → S`; cardinal exponentiation matches via `Cardinal.power_def`.
modifiedPower set as 2^Sae8144f3eaf6
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note`Set.powerset` and `Finset.powerset` realise `2^S`; cardinality via `Fintype.card_finset`.`Set.powerset` and `Finset.powerset` realise `2^S`.
modifiedExponentiation as right adjoint to product6e223ae980ee
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note`CategoryTheory.ihom.adjunction` gives the `tensorLeft A ⊣ ihom A` adjunction, which specialises to the product ⊣ exp adjunction in a cartesian monoidal category.`CategoryTheory.ihom.adjunction` gives the `tensorLeft A ⊣ ihom A` adjunction that specialises to product ⊣ exp.
modifiedCartesian closed categoryab285dea869e
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noteThe dedicated `CartesianClosed` class was deprecated; cartesian closed categories are now `MonoidalClosed C` with `[CartesianMonoidalCategory C]`.Cartesian closed categories are realised as `MonoidalClosed C` with `[CartesianMonoidalCategory C]`.
modifiedTetration and hyperoperation6f5e23b65631
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note`hyperoperation` defines the hyperoperation hierarchy with tetration at level 4.`hyperoperation` defines the hierarchy with tetration at level 4.
modifiedHyperoperation evaluated at (3,3)980feef191b5
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noteSpecific numerical evaluation example; not a Mathlib lemma.Specific numerical evaluation; not a Mathlib lemma.
modifiedn th iterate of a function88b65ca95d59
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note`Nat.iterate f n` is the nth iterate `f^[n]` (with `Function.iterate_*` API).`Nat.iterate f n` is the nth iterate `f^[n]`.
modifiedInverse function notation f^{-1}60a8795030a0
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note`Function.invFun` / `Equiv.symm` formalise the inverse-function notation.`Function.invFun` / `Equiv.symm` formalise inverse-function notation.
modifiedExponentiation by squaring0f0eb14b1a9e
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note`npowBinRec` is Mathlib's repeated-squaring implementation of `npow`, equated to `npowRec` via `npowRec_eq_npowBinRec`.`npowBinRec` is Mathlib's repeated-squaring implementation, equated to `npowRec` via `npowRec_eq_npowBinRec`.
modifiedSpecial limit defining e^x8040f8b4d96a
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note`Real.tendsto_one_add_div_pow_exp` proves `(1 + t/n)^n → exp t` as `n → ∞`.`Real.tendsto_one_add_div_pow_exp` proves `(1 + t/n)^n → exp t`.
modifiedPolar form product rule0e9ec53af12a
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note`Complex.arg_mul` and multiplicativity of `Complex.abs` give the polar product rule.`Complex.arg_mul` plus multiplicativity of `Complex.abs` give the polar product rule.
modifiedCyclic group of order n from element of order n7aa803a2c9f6
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noteMathlib relates `orderOf x = n` to the finite cyclic subgroup `Subgroup.zpowers x` via `orderOf_eq_card_of_zpowers_eq_top`.Mathlib relates `orderOf x = n` to the cyclic subgroup `Subgroup.zpowers x`.
modifiedNumber of primitive elements is φ(q-1)fb11ad420380
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noteCount of generators of a cyclic group of order n is `Nat.totient n`; specialization to finite fields is via cyclicity of the unit group.Count of generators of a cyclic group of order n is `Nat.totient n`; no direct 'φ(q-1) primitives' decl.
addedFermat's little theorem for finite fields43da0459209d
addedNumber of primitive n-th roots of unity is φ(n)40f846f30c35
addedRadical of an ideal is a radical ideal7edc2a7c36a6