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author | Gregor Kleen <gkleen@yggdrasil.li> | 2016-02-03 21:33:46 +0100 |
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committer | Gregor Kleen <gkleen@yggdrasil.li> | 2016-02-03 21:33:46 +0100 |
commit | 7f1293b7afa7574d93c07fd34dc472bb0979a98f (patch) | |
tree | 98bf670814465c36337f50c1e46206770cafed47 | |
parent | 927fe04b9bc95239bc6e6506e74bd47d6edbe0b0 (diff) | |
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minor corrections
-rw-r--r-- | provider/posts/simmons-intro-to-cat-t/1.2.md | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/provider/posts/simmons-intro-to-cat-t/1.2.md b/provider/posts/simmons-intro-to-cat-t/1.2.md index e180c6d..faaf429 100644 --- a/provider/posts/simmons-intro-to-cat-t/1.2.md +++ b/provider/posts/simmons-intro-to-cat-t/1.2.md | |||
@@ -14,7 +14,7 @@ Let $\ca{Pno}$ be the category of objects $(A, \alpha, a)$ where $A$ is a set, $ | |||
14 | $\id$ on $A$ is indeed a function which preserves the structure ($\id \circ \alpha = \alpha = \alpha \circ \id$, $\id(a) = a$) and thus a morphism | 14 | $\id$ on $A$ is indeed a function which preserves the structure ($\id \circ \alpha = \alpha = \alpha \circ \id$, $\id(a) = a$) and thus a morphism |
15 | </div> | 15 | </div> |
16 | 16 | ||
17 | 2. There exists a partial binary operation $\circ$ on the arrows of $\ca{Pno}$ | 17 | 2. There exists an associative partial binary operation $\circ$ on the arrows of $\ca{Pno}$ |
18 | <div class="proof"> | 18 | <div class="proof"> |
19 | Given three objects $(A, \alpha, a), (B, \beta, b), (C, \gamma, c)$ and two functions $g: A \to B$ and $f: B \to C$ the function $f \circ g: A \to C$ is an arrow in $\ca{Pno}$, that is to say, it preserves structure: | 19 | Given three objects $(A, \alpha, a), (B, \beta, b), (C, \gamma, c)$ and two functions $g: A \to B$ and $f: B \to C$ the function $f \circ g: A \to C$ is an arrow in $\ca{Pno}$, that is to say, it preserves structure: |
20 | $$(f \circ g) \circ \alpha = f \circ \beta \circ g = \gamma \circ (f \circ g)$$ | 20 | $$(f \circ g) \circ \alpha = f \circ \beta \circ g = \gamma \circ (f \circ g)$$ |
@@ -62,7 +62,7 @@ Show that such objects and morphisms form a category $\ca{SetD}$ | |||
62 | $\id$ on $A$ is indeed a function which respects the distinguished subset ($\forall \alpha \in a \ldotp \id(\alpha) \in a$) and thus a morphism | 62 | $\id$ on $A$ is indeed a function which respects the distinguished subset ($\forall \alpha \in a \ldotp \id(\alpha) \in a$) and thus a morphism |
63 | </div> | 63 | </div> |
64 | 64 | ||
65 | 2. There exists a partial binary operation $\circ$ on the arrows of $\ca{SetD}$ | 65 | 2. There exists an associative partial binary operation $\circ$ on the arrows of $\ca{SetD}$ |
66 | <div class="proof"> | 66 | <div class="proof"> |
67 | Given three objects $(A, a), (B, b), (C, c)$ and two functions $g: A \to B$ and $f: B \to C$ the function $f \circ g: A \to C$ is an arrow in $\ca{SetD}$, that is to say, $\forall \alpha \in a$: | 67 | Given three objects $(A, a), (B, b), (C, c)$ and two functions $g: A \to B$ and $f: B \to C$ the function $f \circ g: A \to C$ is an arrow in $\ca{SetD}$, that is to say, $\forall \alpha \in a$: |
68 | $$(f \circ g)(\alpha) = f(b) = c$$ | 68 | $$(f \circ g)(\alpha) = f(b) = c$$ |
@@ -83,7 +83,7 @@ We call the category comprised of such objects and arrows $\ca{RelH}$. | |||
83 | 83 | ||
84 | $\id$ on $A$ is indeed a function which respects the binary relation ($\forall a \odot a^\prime \ldotp \id(a) \odot \id(a^\prime)$) and thus a morphism | 84 | $\id$ on $A$ is indeed a function which respects the binary relation ($\forall a \odot a^\prime \ldotp \id(a) \odot \id(a^\prime)$) and thus a morphism |
85 | 85 | ||
86 | 2. There exists a partial binary operation $\circ$ on the arrows of $\ca{RelH}$ | 86 | 2. There exists an associative partial binary operation $\circ$ on the arrows of $\ca{RelH}$ |
87 | 87 | ||
88 | Given three objects $(A, \odot), (B, \oplus), (C, \otimes)$ and two functions $g: A \to B$ and $f: B \to C$ the function $f \circ g: A \to C$ is an arrow in $\ca{RelH}$, that is to say, $\forall a \odot a^\prime$: | 88 | Given three objects $(A, \odot), (B, \oplus), (C, \otimes)$ and two functions $g: A \to B$ and $f: B \to C$ the function $f \circ g: A \to C$ is an arrow in $\ca{RelH}$, that is to say, $\forall a \odot a^\prime$: |
89 | $$a \odot a^\prime \implies g(a) \oplus g(a^\prime) \implies (g \circ f)(a) \otimes (g \circ f)(a^\prime)$$ | 89 | $$a \odot a^\prime \implies g(a) \oplus g(a^\prime) \implies (g \circ f)(a) \otimes (g \circ f)(a^\prime)$$ |
@@ -98,7 +98,7 @@ Topological spaces $(S, \mathcal{O}_S)$, where $S$ is a Set and $\mathcal{O}_S \ | |||
98 | $\id$ on $S$ is indeed a continuous map and thus a morphism | 98 | $\id$ on $S$ is indeed a continuous map and thus a morphism |
99 | </div> | 99 | </div> |
100 | 100 | ||
101 | 2. There exists a partial binary operation $\circ$ on the arrows of $\ca{Top}$ | 101 | 2. There exists an associative partial binary operation $\circ$ on the arrows of $\ca{Top}$ |
102 | <div class="proof"> | 102 | <div class="proof"> |
103 | Given three spaces $(S, \mathcal{O}_S), (T, \mathcal{O}_T), (U, \mathcal{O}_U)$ and two continuous maps $g : S \to T$ and $f : T \to U$ the map $f \circ g : S \to U$ is an arrow in $\ca{Top}$, that is to say, it is contiuous: | 103 | Given three spaces $(S, \mathcal{O}_S), (T, \mathcal{O}_T), (U, \mathcal{O}_U)$ and two continuous maps $g : S \to T$ and $f : T \to U$ the map $f \circ g : S \to U$ is an arrow in $\ca{Top}$, that is to say, it is contiuous: |
104 | $$V \in \mathcal{O}_U \implies g^\leftarrow(V) \in \mathcal{O}_T \implies (f \circ g)^\leftarrow(V) \in \mathcal{O}_S$$ | 104 | $$V \in \mathcal{O}_U \implies g^\leftarrow(V) \in \mathcal{O}_T \implies (f \circ g)^\leftarrow(V) \in \mathcal{O}_S$$ |