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Title: Riemann Integral - Definition
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Series: Real Analysis
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Chapter: Riemann Integral
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YouTube-Title: Real Analysis 51 | Riemann Integral - Definition
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Forum: Ask a question in Mattermost
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Quiz: Test your knowledge
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Exercise Download PDF sheets
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Subtitle on GitHub: ra51_sub_eng.srt missing
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Download bright video: Link on Vimeo
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Timestamps (n/a)
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Subtitle in English (n/a)
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Quiz Content
Q1: What is the correct definition for a bounded function $f$ being Riemann-integrable?
A1: $ \displaystyle \sup \bigg{ \int_a^b \phi(x) dx ~\bigg|~ $ $ \displaystyle \phi(x) \in \mathcal{S}( [a,b] ) , ~ \phi \leq f \bigg} $ $\displaystyle = \inf \bigg{ \int_a^b \phi(x) dx ~\bigg|~ $ $ \displaystyle \phi(x) \in \mathcal{S}( [a,b] ) , ~ \phi \geq f \bigg} $
A2: $ \displaystyle \sup \bigg{ \int_a^b \phi(x) dx ~\bigg|~ $ $ \displaystyle \phi(x) \in \mathcal{S}( [a,b] ) , ~ \phi \geq f \bigg} $ $ \displaystyle = \inf \bigg{ \int_a^b \phi(x) dx ~\bigg|~ $ $ \displaystyle \phi(x) \in \mathcal{S}( [a,b] ) , ~ \phi \leq f \bigg} $
A3: $ \displaystyle \sup \bigg{ \int_a^b \phi(x) dx ~\bigg|~$ $ \displaystyle \phi(x) \in \mathcal{S}( [a,b] ) , ~ \phi \geq f \bigg} $ $ \displaystyle < \inf \bigg{ \int_a^b \phi(x) dx ~\bigg|~$ $ \displaystyle \phi(x) \in \mathcal{S}( [a,b] ) , ~ \phi < f \bigg} $
A4: $ \displaystyle \sup \bigg{ \int_a^b \phi(x) dx ~\bigg|~$ $ \displaystyle \phi(x) \in \mathcal{S}( [a,b] ) , ~ \phi \geq f \bigg} $ $ \displaystyle > \inf \bigg{ \int_a^b \phi(x) dx ~\bigg|~ $ $ \displaystyle \phi(x) \in \mathcal{S}( [a,b] ) , ~ \phi > f \bigg } $
Q2: Let $\psi : [0,2] \rightarrow \mathbb{R}$ be a step function. Is $\psi$ Riemann-integrable?
A1: Yes!
A2: No!
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Last update: 2025-09
