# Metamath Proof Explorer

## Theorem ovolcl

Description: The volume of a set is an extended real number. (Contributed by Mario Carneiro, 16-Mar-2014)

Ref Expression
Assertion ovolcl ${⊢}{A}\subseteq ℝ\to {vol}^{*}\left({A}\right)\in {ℝ}^{*}$

### Proof

Step Hyp Ref Expression
1 eqid ${⊢}\left\{{y}\in {ℝ}^{*}|\exists {f}\in \left({\left(\le \cap {ℝ}^{2}\right)}^{ℕ}\right)\phantom{\rule{.4em}{0ex}}\left({A}\subseteq \bigcup \mathrm{ran}\left(\left(.\right)\circ {f}\right)\wedge {y}=sup\left(\mathrm{ran}seq1\left(+,\left(\left(\mathrm{abs}\circ -\right)\circ {f}\right)\right),{ℝ}^{*},<\right)\right)\right\}=\left\{{y}\in {ℝ}^{*}|\exists {f}\in \left({\left(\le \cap {ℝ}^{2}\right)}^{ℕ}\right)\phantom{\rule{.4em}{0ex}}\left({A}\subseteq \bigcup \mathrm{ran}\left(\left(.\right)\circ {f}\right)\wedge {y}=sup\left(\mathrm{ran}seq1\left(+,\left(\left(\mathrm{abs}\circ -\right)\circ {f}\right)\right),{ℝ}^{*},<\right)\right)\right\}$
2 1 ovolval ${⊢}{A}\subseteq ℝ\to {vol}^{*}\left({A}\right)=sup\left(\left\{{y}\in {ℝ}^{*}|\exists {f}\in \left({\left(\le \cap {ℝ}^{2}\right)}^{ℕ}\right)\phantom{\rule{.4em}{0ex}}\left({A}\subseteq \bigcup \mathrm{ran}\left(\left(.\right)\circ {f}\right)\wedge {y}=sup\left(\mathrm{ran}seq1\left(+,\left(\left(\mathrm{abs}\circ -\right)\circ {f}\right)\right),{ℝ}^{*},<\right)\right)\right\},{ℝ}^{*},<\right)$
3 ssrab2 ${⊢}\left\{{y}\in {ℝ}^{*}|\exists {f}\in \left({\left(\le \cap {ℝ}^{2}\right)}^{ℕ}\right)\phantom{\rule{.4em}{0ex}}\left({A}\subseteq \bigcup \mathrm{ran}\left(\left(.\right)\circ {f}\right)\wedge {y}=sup\left(\mathrm{ran}seq1\left(+,\left(\left(\mathrm{abs}\circ -\right)\circ {f}\right)\right),{ℝ}^{*},<\right)\right)\right\}\subseteq {ℝ}^{*}$
4 infxrcl ${⊢}\left\{{y}\in {ℝ}^{*}|\exists {f}\in \left({\left(\le \cap {ℝ}^{2}\right)}^{ℕ}\right)\phantom{\rule{.4em}{0ex}}\left({A}\subseteq \bigcup \mathrm{ran}\left(\left(.\right)\circ {f}\right)\wedge {y}=sup\left(\mathrm{ran}seq1\left(+,\left(\left(\mathrm{abs}\circ -\right)\circ {f}\right)\right),{ℝ}^{*},<\right)\right)\right\}\subseteq {ℝ}^{*}\to sup\left(\left\{{y}\in {ℝ}^{*}|\exists {f}\in \left({\left(\le \cap {ℝ}^{2}\right)}^{ℕ}\right)\phantom{\rule{.4em}{0ex}}\left({A}\subseteq \bigcup \mathrm{ran}\left(\left(.\right)\circ {f}\right)\wedge {y}=sup\left(\mathrm{ran}seq1\left(+,\left(\left(\mathrm{abs}\circ -\right)\circ {f}\right)\right),{ℝ}^{*},<\right)\right)\right\},{ℝ}^{*},<\right)\in {ℝ}^{*}$
5 3 4 ax-mp ${⊢}sup\left(\left\{{y}\in {ℝ}^{*}|\exists {f}\in \left({\left(\le \cap {ℝ}^{2}\right)}^{ℕ}\right)\phantom{\rule{.4em}{0ex}}\left({A}\subseteq \bigcup \mathrm{ran}\left(\left(.\right)\circ {f}\right)\wedge {y}=sup\left(\mathrm{ran}seq1\left(+,\left(\left(\mathrm{abs}\circ -\right)\circ {f}\right)\right),{ℝ}^{*},<\right)\right)\right\},{ℝ}^{*},<\right)\in {ℝ}^{*}$
6 2 5 eqeltrdi ${⊢}{A}\subseteq ℝ\to {vol}^{*}\left({A}\right)\in {ℝ}^{*}$