{"schema_version":"ocme-site-results-v1","locale":"en","page_type":"derivations","facts":{"questions":36000,"reviewed":36000,"display_candidates":0,"knowledge":302,"guides":299,"paths":59,"batches":360,"families":1441,"atlas":302,"core":80,"evidence":9,"formal_evidence":5,"formal_subjects":4,"lean_files":6,"lean_toolchain":"leanprover/lean4:v4.30.0","question_state":"candidate","english_state":"ai_candidate","question_Lean":"NOT_RUN","canonical_truth_promotion":false},"filters":{"q":"mko-measurable-function"},"kind":"guides","total":1,"pages":1,"page":1,"entries":[{"id":"derivation-mko-measurable-function-01","title":{"zh-Hant":"可測函數：以完整列舉逐一核逆像，並以合成、指示函數與像集陷阱對照","en":"Measurable function: checking every preimage by complete enumeration, with composition, indicators and the image-set trap"},"summary":{"zh-Hant":"X={0,1,2,3}、Σ_X={∅,{0,1},{2,3},X}；Y={0,1,2}、Σ_Y={∅,{0},{1,2},Y}；Z={0,1}、Σ_Z 為冪集。(1) 以完整列舉證明 f=(0↦0,1↦0,2↦1,3↦2) 可測，而 g=(0↦0,1↦1,2↦1,3↦2) 不可測；(2) 證明可測映射的合成可測，並把 φ∘f 讀回為指示函數；(3) 證明指示函數 1_E 可測若且唯若 E∈Σ_X；(4) 用 m 與 k 說明「檢查像集」既會誤拒也會誤收。","en":"X={0,1,2,3}, Σ_X={∅,{0,1},{2,3},X}; Y={0,1,2}, Σ_Y={∅,{0},{1,2},Y}; Z={0,1} with Σ_Z the power set. (1) Prove by complete enumeration that f=(0↦0,1↦0,2↦1,3↦2) is measurable and g=(0↦0,1↦1,2↦1,3↦2) is not; (2) prove that a composite of measurable maps is measurable, and read φ∘f back as an indicator function; (3) prove that an indicator 1_E is measurable exactly when E∈Σ_X; (4) use m and k to show that 'checking images' can both wrongly reject and wrongly accept."},"mko_ids":["mko-measurable-function"]}],"title":"Concept derivation guides"}