LeanMachineLearning exposition

Learning.forall_feedback_evalEnv_ae_eq_eval_action๐Ÿ”—

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forall_feedback_evalEnv_ae_eq_eval_action๐Ÿ”—

LemmaLearning.forall_feedback_evalEnv_ae_eq_eval_action

No docstring.

๐Ÿ”—theorem
Learning.forall_feedback_evalEnv_ae_eq_eval_action.{u_1, u_2, u_3} {๐“ : Type u_1} {๐“จ : Type u_2} {m๐“ : MeasurableSpace ๐“} {m๐“จ : MeasurableSpace ๐“จ} {ฮฉ : Type u_3} {mฮฉ : MeasurableSpace ฮฉ} {alg : Algorithm ๐“ ๐“จ} {f : ๐“ โ†’ ๐“จ} {hf : Measurable f} {P : MeasureTheory.Measure ฮฉ} [MeasureTheory.IsProbabilityMeasure P] {A : โ„• โ†’ ฮฉ โ†’ ๐“} {Y : โ„• โ†’ ฮฉ โ†’ ๐“จ} [StandardBorelSpace ๐“จ] [Nonempty ๐“จ] (h : IsAlgEnvSeq A Y alg (evalEnv f hf) P) : โˆ€แต (ฯ‰ : ฮฉ) โˆ‚P, โˆ€ (n : โ„•), Y n ฯ‰ = f (A n ฯ‰)
Learning.forall_feedback_evalEnv_ae_eq_eval_action.{u_1, u_2, u_3} {๐“ : Type u_1} {๐“จ : Type u_2} {m๐“ : MeasurableSpace ๐“} {m๐“จ : MeasurableSpace ๐“จ} {ฮฉ : Type u_3} {mฮฉ : MeasurableSpace ฮฉ} {alg : Algorithm ๐“ ๐“จ} {f : ๐“ โ†’ ๐“จ} {hf : Measurable f} {P : MeasureTheory.Measure ฮฉ} [MeasureTheory.IsProbabilityMeasure P] {A : โ„• โ†’ ฮฉ โ†’ ๐“} {Y : โ„• โ†’ ฮฉ โ†’ ๐“จ} [StandardBorelSpace ๐“จ] [Nonempty ๐“จ] (h : IsAlgEnvSeq A Y alg (evalEnv f hf) P) : โˆ€แต (ฯ‰ : ฮฉ) โˆ‚P, โˆ€ (n : โ„•), Y n ฯ‰ = f (A n ฯ‰)

Code

lemma forall_feedback_evalEnv_ae_eq_eval_action [StandardBorelSpace ๐“จ] [Nonempty ๐“จ]
    (h : IsAlgEnvSeq A Y alg (evalEnv f hf) P) :
    โˆ€แต ฯ‰ โˆ‚P, โˆ€ n, Y n ฯ‰ = f (A n ฯ‰)
Type uses (3)
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Proof
forall_feedback_onlineEvalEnv_ae_eq_eval_action h

Dependency graph

Type dependencies (3)

Algorithm๐Ÿ”—

StructureLearning.Algorithm

A stochastic, sequential algorithm.

๐Ÿ”—structure
Learning.Algorithm.{u_4, u_5} (๐“ : Type u_4) (๐“จ : Type u_5) [MeasurableSpace ๐“] [MeasurableSpace ๐“จ] : Type (max u_4 u_5)
Learning.Algorithm.{u_4, u_5} (๐“ : Type u_4) (๐“จ : Type u_5) [MeasurableSpace ๐“] [MeasurableSpace ๐“จ] : Type (max u_4 u_5)

Code

structure Algorithm (๐“ ๐“จ : Type*) [MeasurableSpace ๐“] [MeasurableSpace ๐“จ] where
  /-- Policy or sampling rule: distribution of the next action. -/
  policy : (n : โ„•) โ†’ Kernel (Iic n โ†’ ๐“ ร— ๐“จ) ๐“
  /-- The policy is a Markov kernel. -/
  [h_policy : โˆ€ n, IsMarkovKernel (policy n)]
  /-- Distribution of the first action. -/
  p0 : Measure ๐“
  /-- The first action distribution is a probability measure. -/
  [hp0 : IsProbabilityMeasure p0]
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IsAlgEnvSeq๐Ÿ”—

StructureLearning.IsAlgEnvSeq

An algorithm-environment sequence: a sequence of actions and feedbacks generated by an algorithm interacting with an environment.

๐Ÿ”—structure
Learning.IsAlgEnvSeq.{u_1, u_2, u_3} {๐“ : Type u_1} {๐“จ : Type u_2} {ฮฉ : Type u_3} {m๐“ : MeasurableSpace ๐“} {m๐“จ : MeasurableSpace ๐“จ} {mฮฉ : MeasurableSpace ฮฉ} (A : โ„• โ†’ ฮฉ โ†’ ๐“) (Y : โ„• โ†’ ฮฉ โ†’ ๐“จ) (alg : Algorithm ๐“ ๐“จ) (env : Environment ๐“ ๐“จ) (P : MeasureTheory.Measure ฮฉ) [MeasureTheory.IsFiniteMeasure P] : Prop
Learning.IsAlgEnvSeq.{u_1, u_2, u_3} {๐“ : Type u_1} {๐“จ : Type u_2} {ฮฉ : Type u_3} {m๐“ : MeasurableSpace ๐“} {m๐“จ : MeasurableSpace ๐“จ} {mฮฉ : MeasurableSpace ฮฉ} (A : โ„• โ†’ ฮฉ โ†’ ๐“) (Y : โ„• โ†’ ฮฉ โ†’ ๐“จ) (alg : Algorithm ๐“ ๐“จ) (env : Environment ๐“ ๐“จ) (P : MeasureTheory.Measure ฮฉ) [MeasureTheory.IsFiniteMeasure P] : Prop

Code

structure IsAlgEnvSeq
    (A : โ„• โ†’ ฮฉ โ†’ ๐“) (Y : โ„• โ†’ ฮฉ โ†’ ๐“จ) (alg : Algorithm ๐“ ๐“จ) (env : Environment ๐“ ๐“จ)
    (P : Measure ฮฉ) [IsFiniteMeasure P] : Prop where
  /-- The action sequence is measurable. -/
  measurable_action n : Measurable (A n) := by fun_prop
  /-- The feedback sequence is measurable. -/
  measurable_feedback n : Measurable (Y n) := by fun_prop
  /-- The first action has the correct law. -/
  hasLaw_action_zero : HasLaw (fun ฯ‰ โ†ฆ (A 0 ฯ‰)) alg.p0 P
  /-- The first feedback has the correct conditional distribution. -/
  hasCondDistrib_feedback_zero : HasCondDistrib (Y 0) (A 0) env.ฮฝ0 P
  /-- The next action has the correct conditional distribution given the history. -/
  hasCondDistrib_action n :
    HasCondDistrib (A (n + 1)) (history A Y n) (alg.policy n) P
  /-- The next feedback has the correct conditional distribution given the history and
  next action. -/
  hasCondDistrib_feedback n :
    HasCondDistrib (Y (n + 1)) (fun ฯ‰ โ†ฆ (history A Y n ฯ‰, A (n + 1) ฯ‰))
      (env.feedback n) P
Type uses (3)
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evalEnv๐Ÿ”—

DefinitionLearning.evalEnv

The evaluation environment where the feedback is given by evaluating a fixed measurable function f at the chosen action.

๐Ÿ”—def
Learning.evalEnv.{u_1, u_2} {๐“ : Type u_1} {๐“จ : Type u_2} {m๐“ : MeasurableSpace ๐“} {m๐“จ : MeasurableSpace ๐“จ} (f : ๐“ โ†’ ๐“จ) (hf : Measurable f) : Environment ๐“ ๐“จ
Learning.evalEnv.{u_1, u_2} {๐“ : Type u_1} {๐“จ : Type u_2} {m๐“ : MeasurableSpace ๐“} {m๐“จ : MeasurableSpace ๐“จ} (f : ๐“ โ†’ ๐“จ) (hf : Measurable f) : Environment ๐“ ๐“จ

Code

noncomputable def evalEnv (f : ๐“ โ†’ ๐“จ) (hf : Measurable f) := onlineEvalEnv (fun _ โ†ฆ f) (fun _ โ†ฆ hf)
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Environment๐Ÿ”—

StructureLearning.Environment

A stochastic environment.

๐Ÿ”—structure
Learning.Environment.{u_4, u_5} (๐“ : Type u_4) (๐“จ : Type u_5) [MeasurableSpace ๐“] [MeasurableSpace ๐“จ] : Type (max u_4 u_5)
Learning.Environment.{u_4, u_5} (๐“ : Type u_4) (๐“จ : Type u_5) [MeasurableSpace ๐“] [MeasurableSpace ๐“จ] : Type (max u_4 u_5)

Code

structure Environment (๐“ ๐“จ : Type*) [MeasurableSpace ๐“] [MeasurableSpace ๐“จ] where
  /-- Distribution of the next observation as function of the past history. -/
  feedback : (n : โ„•) โ†’ Kernel ((Iic n โ†’ ๐“ ร— ๐“จ) ร— ๐“) ๐“จ
  /-- The feedback kernels are Markov kernels. -/
  [h_feedback : โˆ€ n, IsMarkovKernel (feedback n)]
  /-- Distribution of the first observation given the first action. -/
  ฮฝ0 : Kernel ๐“ ๐“จ
  /-- The initial observation kernel is a Markov kernel. -/
  [hp0 : IsMarkovKernel ฮฝ0]
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history๐Ÿ”—

DefinitionLearning.history

History of the algorithm-environment sequence up to time n.

๐Ÿ”—def
Learning.history.{u_1, u_2, u_3} {๐“ : Type u_1} {๐“จ : Type u_2} {ฮฉ : Type u_3} (A : โ„• โ†’ ฮฉ โ†’ ๐“) (Y : โ„• โ†’ ฮฉ โ†’ ๐“จ) (n : โ„•) (ฯ‰ : ฮฉ) : โ†ฅ(Finset.Iic n) โ†’ ๐“ ร— ๐“จ
Learning.history.{u_1, u_2, u_3} {๐“ : Type u_1} {๐“จ : Type u_2} {ฮฉ : Type u_3} (A : โ„• โ†’ ฮฉ โ†’ ๐“) (Y : โ„• โ†’ ฮฉ โ†’ ๐“จ) (n : โ„•) (ฯ‰ : ฮฉ) : โ†ฅ(Finset.Iic n) โ†’ ๐“ ร— ๐“จ

Code

def history (A : โ„• โ†’ ฮฉ โ†’ ๐“) (Y : โ„• โ†’ ฮฉ โ†’ ๐“จ) (n : โ„•) (ฯ‰ : ฮฉ) : Iic n โ†’ ๐“ ร— ๐“จ :=
  fun i โ†ฆ (A i ฯ‰, Y i ฯ‰)
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obliviousEnv๐Ÿ”—

DefinitionLearning.obliviousEnv

An oblivious environment, in which the distribution of the next feedback depends only on the last action, but in a possibly time-dependent manner.

๐Ÿ”—def
Learning.obliviousEnv.{u_1, u_2} {๐“ : Type u_1} {๐“จ : Type u_2} {m๐“ : MeasurableSpace ๐“} {m๐“จ : MeasurableSpace ๐“จ} (ฮฝ : โ„• โ†’ ProbabilityTheory.Kernel ๐“ ๐“จ) [โˆ€ (n : โ„•), ProbabilityTheory.IsMarkovKernel (ฮฝ n)] : Environment ๐“ ๐“จ
Learning.obliviousEnv.{u_1, u_2} {๐“ : Type u_1} {๐“จ : Type u_2} {m๐“ : MeasurableSpace ๐“} {m๐“จ : MeasurableSpace ๐“จ} (ฮฝ : โ„• โ†’ ProbabilityTheory.Kernel ๐“ ๐“จ) [โˆ€ (n : โ„•), ProbabilityTheory.IsMarkovKernel (ฮฝ n)] : Environment ๐“ ๐“จ

Code

def obliviousEnv (ฮฝ : โ„• โ†’ Kernel ๐“ ๐“จ) [โˆ€ n, IsMarkovKernel (ฮฝ n)] : Environment ๐“ ๐“จ where
  feedback n := (ฮฝ (n + 1)).prodMkLeft _
  ฮฝ0 := ฮฝ 0
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onlineEvalEnv๐Ÿ”—

DefinitionLearning.onlineEvalEnv

The evaluation environment where the feedback is given by evaluating a fixed measurable function f at the chosen action.

๐Ÿ”—def
Learning.onlineEvalEnv.{u_1, u_2} {๐“ : Type u_1} {๐“จ : Type u_2} {m๐“ : MeasurableSpace ๐“} {m๐“จ : MeasurableSpace ๐“จ} (g : โ„• โ†’ ๐“ โ†’ ๐“จ) (hg : โˆ€ (n : โ„•), Measurable (g n)) : Environment ๐“ ๐“จ
Learning.onlineEvalEnv.{u_1, u_2} {๐“ : Type u_1} {๐“จ : Type u_2} {m๐“ : MeasurableSpace ๐“} {m๐“จ : MeasurableSpace ๐“จ} (g : โ„• โ†’ ๐“ โ†’ ๐“จ) (hg : โˆ€ (n : โ„•), Measurable (g n)) : Environment ๐“ ๐“จ

Code

noncomputable def onlineEvalEnv (g : โ„• โ†’ ๐“ โ†’ ๐“จ) (hg : โˆ€ n, Measurable (g n)) :=
  obliviousEnv (fun n โ†ฆ Kernel.deterministic (g n) (hg n))
Type uses (1)
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