diff --git a/src/analysis.lagda.md b/src/analysis.lagda.md new file mode 100644 index 0000000000..02e077e8dc --- /dev/null +++ b/src/analysis.lagda.md @@ -0,0 +1,8 @@ +# Analysis + +```agda +module analysis where + +open import analysis.commutative-rings-in-complete-metric-spaces public +open import analysis.series public +``` diff --git a/src/analysis/commutative-rings-in-complete-metric-spaces.lagda.md b/src/analysis/commutative-rings-in-complete-metric-spaces.lagda.md new file mode 100644 index 0000000000..d746dfe0af --- /dev/null +++ b/src/analysis/commutative-rings-in-complete-metric-spaces.lagda.md @@ -0,0 +1,100 @@ +# Commutative rings in complete metric spaces + +```agda +module analysis.commutative-rings-in-complete-metric-spaces where +``` + +
Imports + +```agda +open import commutative-algebra.commutative-rings + +open import foundation.dependent-pair-types +open import foundation.identity-types +open import foundation.universe-levels + +open import metric-spaces.complete-metric-spaces +open import metric-spaces.metric-spaces +open import metric-spaces.metric-structures +open import metric-spaces.premetric-spaces +open import metric-spaces.premetric-structures +``` + +
+ +## Idea + +A commutative ring in a complete metric space is a setting in which power series +and their convergence can be considered. + +## Definition + +```agda +Commutative-Ring-In-Complete-Metric-Space : + (l1 l2 : Level) → UU (lsuc l1 ⊔ lsuc l2) +Commutative-Ring-In-Complete-Metric-Space l1 l2 = + Σ ( Commutative-Ring l1) + ( λ R → + Σ ( Premetric l2 (type-Commutative-Ring R)) + ( λ μ → + Σ ( is-metric-Premetric μ) + ( λ is-metric-μ → + is-complete-Metric-Space + ( (type-Commutative-Ring R , μ) , is-metric-μ)))) + +module _ + {l1 l2 : Level} (RM : Commutative-Ring-In-Complete-Metric-Space l1 l2) + where + + commutative-ring-Commutative-Ring-In-Complete-Metric-Space : + Commutative-Ring l1 + commutative-ring-Commutative-Ring-In-Complete-Metric-Space = pr1 RM + + type-Commutative-Ring-In-Complete-Metric-Space : UU l1 + type-Commutative-Ring-In-Complete-Metric-Space = + type-Commutative-Ring + ( commutative-ring-Commutative-Ring-In-Complete-Metric-Space) + + structure-Commutative-Ring-In-Complete-Metric-Space : + Premetric l2 type-Commutative-Ring-In-Complete-Metric-Space + structure-Commutative-Ring-In-Complete-Metric-Space = pr1 (pr2 RM) + + is-metric-structure-Commutative-Ring-In-Complete-Metric-Space : + is-metric-Premetric structure-Commutative-Ring-In-Complete-Metric-Space + is-metric-structure-Commutative-Ring-In-Complete-Metric-Space = + pr1 (pr2 (pr2 RM)) + + metric-space-Commutative-Ring-In-Complete-Metric-Space : Metric-Space l1 l2 + metric-space-Commutative-Ring-In-Complete-Metric-Space = + ( ( type-Commutative-Ring-In-Complete-Metric-Space , + structure-Commutative-Ring-In-Complete-Metric-Space) , + is-metric-structure-Commutative-Ring-In-Complete-Metric-Space) + + is-complete-metric-space-Commutative-Ring-In-Complete-Metric-Space : + is-complete-Metric-Space + metric-space-Commutative-Ring-In-Complete-Metric-Space + is-complete-metric-space-Commutative-Ring-In-Complete-Metric-Space = + pr2 (pr2 (pr2 RM)) + + complete-metric-space-Commutative-Ring-In-Complete-Metric-Space : + Complete-Metric-Space l1 l2 + complete-metric-space-Commutative-Ring-In-Complete-Metric-Space = + ( metric-space-Commutative-Ring-In-Complete-Metric-Space , + is-complete-metric-space-Commutative-Ring-In-Complete-Metric-Space) +``` + +### Construction + +```agda +commutative-ring-in-complete-metric-space-Commutative-Ring-Complete-Metric-Space : + {l1 l2 : Level} → + (R : Commutative-Ring l1) (M : Complete-Metric-Space l1 l2) → + (type-Commutative-Ring R = type-Complete-Metric-Space M) → + Commutative-Ring-In-Complete-Metric-Space l1 l2 +commutative-ring-in-complete-metric-space-Commutative-Ring-Complete-Metric-Space + R M refl = + ( R , + structure-Complete-Metric-Space M , + is-metric-structure-Complete-Metric-Space M , + is-complete-metric-space-Complete-Metric-Space M) +``` diff --git a/src/analysis/series.lagda.md b/src/analysis/series.lagda.md new file mode 100644 index 0000000000..82fac5b6d1 --- /dev/null +++ b/src/analysis/series.lagda.md @@ -0,0 +1,75 @@ +# Series + +```agda +module analysis.series where +``` + +
Imports + +```agda +open import analysis.commutative-rings-in-complete-metric-spaces + +open import commutative-algebra.sums-of-finite-sequences-of-elements-commutative-rings + +open import foundation.dependent-pair-types +open import foundation.propositions +open import foundation.sequences +open import foundation.universe-levels + +open import metric-spaces.limits-of-sequences-metric-spaces + +open import univalent-combinatorics.standard-finite-types +``` + +
+ +## Idea + +A series is an infinite sum taken over the natural numbers. If it has a limit, +it is said to converge, otherwise it is said to diverge. + +## Definition + +```agda +record + series + {l1 l2 : Level} (RM : Commutative-Ring-In-Complete-Metric-Space l1 l2) : + UU l1 + where + + constructor series-terms + + field + terms-series : sequence (type-Commutative-Ring-In-Complete-Metric-Space RM) + +open series public + +module _ + {l1 l2 : Level} + (RM : Commutative-Ring-In-Complete-Metric-Space l1 l2) (σ : series RM) + where + + partial-sums-series : + sequence (type-Commutative-Ring-In-Complete-Metric-Space RM) + partial-sums-series n = + sum-fin-sequence-type-Commutative-Ring + ( commutative-ring-Commutative-Ring-In-Complete-Metric-Space RM) + ( n) + ( λ k → terms-series σ (nat-Fin n k)) + + is-convergent-series : UU (l1 ⊔ l2) + is-convergent-series = + has-limit-sequence-Metric-Space + ( metric-space-Commutative-Ring-In-Complete-Metric-Space RM) + ( partial-sums-series) + + is-prop-is-convergent-series : is-prop converges-series + is-prop-is-convergent-series = + is-prop-has-limit-sequence-Metric-Space + ( metric-space-Commutative-Ring-In-Complete-Metric-Space RM) + ( partial-sums-series) + + is-convergent-prop-series : Prop (l1 ⊔ l2) + pr1 is-convergent-prop-series = is-convergent-series + pr2 is-convergent-prop-series = is-prop-is-convergent-series +``` diff --git a/src/metric-spaces/complete-metric-spaces.lagda.md b/src/metric-spaces/complete-metric-spaces.lagda.md index 6a311ad7be..b48a3f2a9f 100644 --- a/src/metric-spaces/complete-metric-spaces.lagda.md +++ b/src/metric-spaces/complete-metric-spaces.lagda.md @@ -21,6 +21,8 @@ open import foundation.universe-levels open import metric-spaces.cauchy-approximations-metric-spaces open import metric-spaces.convergent-cauchy-approximations-metric-spaces open import metric-spaces.metric-spaces +open import metric-spaces.metric-structures +open import metric-spaces.premetric-structures ``` @@ -85,6 +87,15 @@ module _ is-complete-metric-space-Complete-Metric-Space : is-complete-Metric-Space metric-space-Complete-Metric-Space is-complete-metric-space-Complete-Metric-Space = pr2 A + + structure-Complete-Metric-Space : Premetric l2 type-Complete-Metric-Space + structure-Complete-Metric-Space = + structure-Metric-Space metric-space-Complete-Metric-Space + + is-metric-structure-Complete-Metric-Space : + is-metric-Premetric structure-Complete-Metric-Space + is-metric-structure-Complete-Metric-Space = + is-metric-structure-Metric-Space metric-space-Complete-Metric-Space ``` ### The equivalence between Cauchy approximations and convergent Cauchy approximations in a complete metric space