Is it possible to give , in economics, an example of a relation ( set of ordered pairs) that is not a function? Planned maintenance scheduled April 23, 2019 at 00:00UTC (8:00pm US/Eastern) Announcing the arrival of Valued Associate #679: Cesar Manara Unicorn Meta Zoo #1: Why another podcast?Topological concepts in economic theoryUse of mathematics and imprecise definition of termsHow to show that a homothetic utility function has demand functions which are linear in incomeDoing a PhD Economics without background in formal theorems?Mathematics in modelling: Issues?Multivariable Utility functionsWhat are directional derivatives used for in economics?General model of economics, economics as mathematical structureCriticism of Math in EconomicsOpen Foundational Problems in Mathematical Economics
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Is it possible to give , in economics, an example of a relation ( set of ordered pairs) that is not a function?
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Is it possible to give , in economics, an example of a relation ( set of ordered pairs) that is not a function?
Planned maintenance scheduled April 23, 2019 at 00:00UTC (8:00pm US/Eastern)
Announcing the arrival of Valued Associate #679: Cesar Manara
Unicorn Meta Zoo #1: Why another podcast?Topological concepts in economic theoryUse of mathematics and imprecise definition of termsHow to show that a homothetic utility function has demand functions which are linear in incomeDoing a PhD Economics without background in formal theorems?Mathematics in modelling: Issues?Multivariable Utility functionsWhat are directional derivatives used for in economics?General model of economics, economics as mathematical structureCriticism of Math in EconomicsOpen Foundational Problems in Mathematical Economics
$begingroup$
In mathematics, some relations ( sets of ordered pairs) are not functions.
I know economists make use of functions.
But do they also consider relations that are not functions.
In which branch of economics could "non-functional" relations be useful?
macroeconomics microeconomics mathematical-economics
New contributor
$endgroup$
add a comment |
$begingroup$
In mathematics, some relations ( sets of ordered pairs) are not functions.
I know economists make use of functions.
But do they also consider relations that are not functions.
In which branch of economics could "non-functional" relations be useful?
macroeconomics microeconomics mathematical-economics
New contributor
$endgroup$
$begingroup$
In "I know mathematicians make use of functions. But do they also consider relations that are not functions.", the "they" seems to be refer to "mathematicians". Do you mean to ask whether mathematicians make use of relations that are not functions? Or more in line with you last line whether "economists" do?
$endgroup$
– Martin Van der Linden
6 hours ago
$begingroup$
@MartinVanderLinden. It was a mistake. Thanks.
$endgroup$
– Eleonore Saint James
6 hours ago
$begingroup$
You could edit your question if it was a mistake.
$endgroup$
– Martin Van der Linden
5 hours ago
1
$begingroup$
I'm not sure how much asking this in the context of economics adds. Unless you look at really abstract example, most examples from math will have applications to economics.
$endgroup$
– Acccumulation
1 hour ago
add a comment |
$begingroup$
In mathematics, some relations ( sets of ordered pairs) are not functions.
I know economists make use of functions.
But do they also consider relations that are not functions.
In which branch of economics could "non-functional" relations be useful?
macroeconomics microeconomics mathematical-economics
New contributor
$endgroup$
In mathematics, some relations ( sets of ordered pairs) are not functions.
I know economists make use of functions.
But do they also consider relations that are not functions.
In which branch of economics could "non-functional" relations be useful?
macroeconomics microeconomics mathematical-economics
macroeconomics microeconomics mathematical-economics
New contributor
New contributor
edited 6 hours ago
Eleonore Saint James
New contributor
asked 7 hours ago
Eleonore Saint JamesEleonore Saint James
1063
1063
New contributor
New contributor
$begingroup$
In "I know mathematicians make use of functions. But do they also consider relations that are not functions.", the "they" seems to be refer to "mathematicians". Do you mean to ask whether mathematicians make use of relations that are not functions? Or more in line with you last line whether "economists" do?
$endgroup$
– Martin Van der Linden
6 hours ago
$begingroup$
@MartinVanderLinden. It was a mistake. Thanks.
$endgroup$
– Eleonore Saint James
6 hours ago
$begingroup$
You could edit your question if it was a mistake.
$endgroup$
– Martin Van der Linden
5 hours ago
1
$begingroup$
I'm not sure how much asking this in the context of economics adds. Unless you look at really abstract example, most examples from math will have applications to economics.
$endgroup$
– Acccumulation
1 hour ago
add a comment |
$begingroup$
In "I know mathematicians make use of functions. But do they also consider relations that are not functions.", the "they" seems to be refer to "mathematicians". Do you mean to ask whether mathematicians make use of relations that are not functions? Or more in line with you last line whether "economists" do?
$endgroup$
– Martin Van der Linden
6 hours ago
$begingroup$
@MartinVanderLinden. It was a mistake. Thanks.
$endgroup$
– Eleonore Saint James
6 hours ago
$begingroup$
You could edit your question if it was a mistake.
$endgroup$
– Martin Van der Linden
5 hours ago
1
$begingroup$
I'm not sure how much asking this in the context of economics adds. Unless you look at really abstract example, most examples from math will have applications to economics.
$endgroup$
– Acccumulation
1 hour ago
$begingroup$
In "I know mathematicians make use of functions. But do they also consider relations that are not functions.", the "they" seems to be refer to "mathematicians". Do you mean to ask whether mathematicians make use of relations that are not functions? Or more in line with you last line whether "economists" do?
$endgroup$
– Martin Van der Linden
6 hours ago
$begingroup$
In "I know mathematicians make use of functions. But do they also consider relations that are not functions.", the "they" seems to be refer to "mathematicians". Do you mean to ask whether mathematicians make use of relations that are not functions? Or more in line with you last line whether "economists" do?
$endgroup$
– Martin Van der Linden
6 hours ago
$begingroup$
@MartinVanderLinden. It was a mistake. Thanks.
$endgroup$
– Eleonore Saint James
6 hours ago
$begingroup$
@MartinVanderLinden. It was a mistake. Thanks.
$endgroup$
– Eleonore Saint James
6 hours ago
$begingroup$
You could edit your question if it was a mistake.
$endgroup$
– Martin Van der Linden
5 hours ago
$begingroup$
You could edit your question if it was a mistake.
$endgroup$
– Martin Van der Linden
5 hours ago
1
1
$begingroup$
I'm not sure how much asking this in the context of economics adds. Unless you look at really abstract example, most examples from math will have applications to economics.
$endgroup$
– Acccumulation
1 hour ago
$begingroup$
I'm not sure how much asking this in the context of economics adds. Unless you look at really abstract example, most examples from math will have applications to economics.
$endgroup$
– Acccumulation
1 hour ago
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
I feel that your question might be a little broad, but there are certainly many areas of economics where non-functional relations are used. Two simple examples (there are many others):
- One of the most fundamental models of behavior in economics relies on the idea that choices can be represented by "preferences" which mathematically are binary relations that do not have to be functions (they very often are not, e.g., $A succ B succ C$ is not a function, since $succ = (A,B), (A,C), (B,C)$.
- Economics also relies on correspondences, or ``multivalued" functions (which, depending on the definition, can be just another way to view binary relations). Correspondences are used in a lot of subfields of economics but perhaps most notably in consumer theory, where the choice set of consumer with preference $succeq$ and budget set $B$ can be a whole subset of the consumption space $C(succ,B) subseteq X$ (where $X$ denotes the consumption space).
$endgroup$
$begingroup$
Example 1 can be represented as a function though, relating the set of alternatives $S$ to the powerset of $S$. It is not very unusual to see it represented this way. It's perfectly fine (mathematically) to have a function relate elements to sets. It's just not a function from the set to itself in that case. Example 2 has the same issue.
$endgroup$
– John Doucette
2 hours ago
$begingroup$
Sure. Every relation $R subseteq (Atimes B)$ can be somewhat "equivalently" represented as a function $f colon A rightarrow 2^B$ such that for all $a in A$ and all $b in B$, we have $b in f(a)$ if and only if $(a,b) in R$. It remains that $succ$ is not itself a function. I think it's fair to say that binary relations like $succ$ are "useful" in economics. Since the OP's question was about "relations that are not functions and are useful in economics" that hopefully provides a good example.
$endgroup$
– Martin Van der Linden
1 hour ago
add a comment |
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$begingroup$
I feel that your question might be a little broad, but there are certainly many areas of economics where non-functional relations are used. Two simple examples (there are many others):
- One of the most fundamental models of behavior in economics relies on the idea that choices can be represented by "preferences" which mathematically are binary relations that do not have to be functions (they very often are not, e.g., $A succ B succ C$ is not a function, since $succ = (A,B), (A,C), (B,C)$.
- Economics also relies on correspondences, or ``multivalued" functions (which, depending on the definition, can be just another way to view binary relations). Correspondences are used in a lot of subfields of economics but perhaps most notably in consumer theory, where the choice set of consumer with preference $succeq$ and budget set $B$ can be a whole subset of the consumption space $C(succ,B) subseteq X$ (where $X$ denotes the consumption space).
$endgroup$
$begingroup$
Example 1 can be represented as a function though, relating the set of alternatives $S$ to the powerset of $S$. It is not very unusual to see it represented this way. It's perfectly fine (mathematically) to have a function relate elements to sets. It's just not a function from the set to itself in that case. Example 2 has the same issue.
$endgroup$
– John Doucette
2 hours ago
$begingroup$
Sure. Every relation $R subseteq (Atimes B)$ can be somewhat "equivalently" represented as a function $f colon A rightarrow 2^B$ such that for all $a in A$ and all $b in B$, we have $b in f(a)$ if and only if $(a,b) in R$. It remains that $succ$ is not itself a function. I think it's fair to say that binary relations like $succ$ are "useful" in economics. Since the OP's question was about "relations that are not functions and are useful in economics" that hopefully provides a good example.
$endgroup$
– Martin Van der Linden
1 hour ago
add a comment |
$begingroup$
I feel that your question might be a little broad, but there are certainly many areas of economics where non-functional relations are used. Two simple examples (there are many others):
- One of the most fundamental models of behavior in economics relies on the idea that choices can be represented by "preferences" which mathematically are binary relations that do not have to be functions (they very often are not, e.g., $A succ B succ C$ is not a function, since $succ = (A,B), (A,C), (B,C)$.
- Economics also relies on correspondences, or ``multivalued" functions (which, depending on the definition, can be just another way to view binary relations). Correspondences are used in a lot of subfields of economics but perhaps most notably in consumer theory, where the choice set of consumer with preference $succeq$ and budget set $B$ can be a whole subset of the consumption space $C(succ,B) subseteq X$ (where $X$ denotes the consumption space).
$endgroup$
$begingroup$
Example 1 can be represented as a function though, relating the set of alternatives $S$ to the powerset of $S$. It is not very unusual to see it represented this way. It's perfectly fine (mathematically) to have a function relate elements to sets. It's just not a function from the set to itself in that case. Example 2 has the same issue.
$endgroup$
– John Doucette
2 hours ago
$begingroup$
Sure. Every relation $R subseteq (Atimes B)$ can be somewhat "equivalently" represented as a function $f colon A rightarrow 2^B$ such that for all $a in A$ and all $b in B$, we have $b in f(a)$ if and only if $(a,b) in R$. It remains that $succ$ is not itself a function. I think it's fair to say that binary relations like $succ$ are "useful" in economics. Since the OP's question was about "relations that are not functions and are useful in economics" that hopefully provides a good example.
$endgroup$
– Martin Van der Linden
1 hour ago
add a comment |
$begingroup$
I feel that your question might be a little broad, but there are certainly many areas of economics where non-functional relations are used. Two simple examples (there are many others):
- One of the most fundamental models of behavior in economics relies on the idea that choices can be represented by "preferences" which mathematically are binary relations that do not have to be functions (they very often are not, e.g., $A succ B succ C$ is not a function, since $succ = (A,B), (A,C), (B,C)$.
- Economics also relies on correspondences, or ``multivalued" functions (which, depending on the definition, can be just another way to view binary relations). Correspondences are used in a lot of subfields of economics but perhaps most notably in consumer theory, where the choice set of consumer with preference $succeq$ and budget set $B$ can be a whole subset of the consumption space $C(succ,B) subseteq X$ (where $X$ denotes the consumption space).
$endgroup$
I feel that your question might be a little broad, but there are certainly many areas of economics where non-functional relations are used. Two simple examples (there are many others):
- One of the most fundamental models of behavior in economics relies on the idea that choices can be represented by "preferences" which mathematically are binary relations that do not have to be functions (they very often are not, e.g., $A succ B succ C$ is not a function, since $succ = (A,B), (A,C), (B,C)$.
- Economics also relies on correspondences, or ``multivalued" functions (which, depending on the definition, can be just another way to view binary relations). Correspondences are used in a lot of subfields of economics but perhaps most notably in consumer theory, where the choice set of consumer with preference $succeq$ and budget set $B$ can be a whole subset of the consumption space $C(succ,B) subseteq X$ (where $X$ denotes the consumption space).
edited 5 hours ago
answered 6 hours ago
Martin Van der LindenMartin Van der Linden
3,7011240
3,7011240
$begingroup$
Example 1 can be represented as a function though, relating the set of alternatives $S$ to the powerset of $S$. It is not very unusual to see it represented this way. It's perfectly fine (mathematically) to have a function relate elements to sets. It's just not a function from the set to itself in that case. Example 2 has the same issue.
$endgroup$
– John Doucette
2 hours ago
$begingroup$
Sure. Every relation $R subseteq (Atimes B)$ can be somewhat "equivalently" represented as a function $f colon A rightarrow 2^B$ such that for all $a in A$ and all $b in B$, we have $b in f(a)$ if and only if $(a,b) in R$. It remains that $succ$ is not itself a function. I think it's fair to say that binary relations like $succ$ are "useful" in economics. Since the OP's question was about "relations that are not functions and are useful in economics" that hopefully provides a good example.
$endgroup$
– Martin Van der Linden
1 hour ago
add a comment |
$begingroup$
Example 1 can be represented as a function though, relating the set of alternatives $S$ to the powerset of $S$. It is not very unusual to see it represented this way. It's perfectly fine (mathematically) to have a function relate elements to sets. It's just not a function from the set to itself in that case. Example 2 has the same issue.
$endgroup$
– John Doucette
2 hours ago
$begingroup$
Sure. Every relation $R subseteq (Atimes B)$ can be somewhat "equivalently" represented as a function $f colon A rightarrow 2^B$ such that for all $a in A$ and all $b in B$, we have $b in f(a)$ if and only if $(a,b) in R$. It remains that $succ$ is not itself a function. I think it's fair to say that binary relations like $succ$ are "useful" in economics. Since the OP's question was about "relations that are not functions and are useful in economics" that hopefully provides a good example.
$endgroup$
– Martin Van der Linden
1 hour ago
$begingroup$
Example 1 can be represented as a function though, relating the set of alternatives $S$ to the powerset of $S$. It is not very unusual to see it represented this way. It's perfectly fine (mathematically) to have a function relate elements to sets. It's just not a function from the set to itself in that case. Example 2 has the same issue.
$endgroup$
– John Doucette
2 hours ago
$begingroup$
Example 1 can be represented as a function though, relating the set of alternatives $S$ to the powerset of $S$. It is not very unusual to see it represented this way. It's perfectly fine (mathematically) to have a function relate elements to sets. It's just not a function from the set to itself in that case. Example 2 has the same issue.
$endgroup$
– John Doucette
2 hours ago
$begingroup$
Sure. Every relation $R subseteq (Atimes B)$ can be somewhat "equivalently" represented as a function $f colon A rightarrow 2^B$ such that for all $a in A$ and all $b in B$, we have $b in f(a)$ if and only if $(a,b) in R$. It remains that $succ$ is not itself a function. I think it's fair to say that binary relations like $succ$ are "useful" in economics. Since the OP's question was about "relations that are not functions and are useful in economics" that hopefully provides a good example.
$endgroup$
– Martin Van der Linden
1 hour ago
$begingroup$
Sure. Every relation $R subseteq (Atimes B)$ can be somewhat "equivalently" represented as a function $f colon A rightarrow 2^B$ such that for all $a in A$ and all $b in B$, we have $b in f(a)$ if and only if $(a,b) in R$. It remains that $succ$ is not itself a function. I think it's fair to say that binary relations like $succ$ are "useful" in economics. Since the OP's question was about "relations that are not functions and are useful in economics" that hopefully provides a good example.
$endgroup$
– Martin Van der Linden
1 hour ago
add a comment |
Eleonore Saint James is a new contributor. Be nice, and check out our Code of Conduct.
Eleonore Saint James is a new contributor. Be nice, and check out our Code of Conduct.
Eleonore Saint James is a new contributor. Be nice, and check out our Code of Conduct.
Eleonore Saint James is a new contributor. Be nice, and check out our Code of Conduct.
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$begingroup$
In "I know mathematicians make use of functions. But do they also consider relations that are not functions.", the "they" seems to be refer to "mathematicians". Do you mean to ask whether mathematicians make use of relations that are not functions? Or more in line with you last line whether "economists" do?
$endgroup$
– Martin Van der Linden
6 hours ago
$begingroup$
@MartinVanderLinden. It was a mistake. Thanks.
$endgroup$
– Eleonore Saint James
6 hours ago
$begingroup$
You could edit your question if it was a mistake.
$endgroup$
– Martin Van der Linden
5 hours ago
1
$begingroup$
I'm not sure how much asking this in the context of economics adds. Unless you look at really abstract example, most examples from math will have applications to economics.
$endgroup$
– Acccumulation
1 hour ago