[#P2956] Erdős's sum-distinct set problem for real numbers
Contents
Problem. Erdős Problem 1: A finite set of real numbers $A$ is said to be a sum-distinct set for $N \in \mathbb{N}$ if $A \subseteq (0, N]$ and the subset sums $\sum_{a \in S} a$ differ by at least $1$ for all distinct subsets $S \subseteq A$. That is, for any two distinct subsets $S_1, S_2 \subseteq A$, we have $1 \leq |\sum_{a \in S_1} a - \sum_{a \in S_2} a|$. Determine whether there exists a positive real constant $C$ such that for every nonzero natural number $N$ and every finite set $A \subseteq (0, N]$ that is sum-distinct for $N$, the inequality $C \cdot 2^{|A|} < N$ holds.
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Definitions and notation
1Context
This is a generalization of Erdős's classical problem on sum-distinct sets of integers to the real number setting. The integer version asks whether $N \gg 2^n$ for a sum-distinct set $A \subseteq \{1, \ldots, N\}$ with $|A| = n$, where all subset sums are distinct. The real version relaxes the distinctness condition to require only that subset sums differ by at least $1$.
2Definitions
Definition 1 (A finite set of real numbers $A$). A finite set of real numbers $A$ is said to be a sum-distinct set for $N \in \mathbb{N}$ if $A \subseteq (0, N]$ and for any two distinct subsets $S_1, S_2 \subseteq A$, the inequality $1 \leq |\sum_{a \in S_1} a - \sum_{a \in S_2} a|$ holds.
3What counts as a solution
- Give a rigorous proof or counterexample that completely resolves this statement: Erdős Problem 1: A finite set of real numbers $A$ is said to be a sum-distinct set for $N \in \mathbb{N}$ if $A \subseteq (0, N]$ and the subset sums $\sum_{a \in S} a$ differ by at least $1$ for all distinct subsets $S \subseteq A$. That is, for any two distinct subsets $S_1, S_2 \subseteq A$, we have $1 \leq |\sum_{a \in S_1} a - \sum_{a \in S_2} a|$. Determine whether there exists a positive real constant $C$ such that for every nonzero natural number $N$ and every finite set $A \subseteq (0, N]$ that is sum-distinct for $N$, the inequality $C \cdot 2^{|A|} < N$ holds.
1Status
Saved packet · July 31, 2026
Saved packet status (Current status and unresolved remainder). OPEN as of 2026-07-31. The maintained Erdős Problems database at commit 8138974387d9030542daabe67faaa33eff9356f8 lists Problem 1 as open. The unresolved remainder is the full displayed statement. Give a rigorous proof or counterexample that completely resolves this statement: Erdős Problem 1: A finite set of real numbers $A$ is said to be a sum-distinct set for $N \in \mathbb{N}$ if $A \subseteq (0, N]$ and the subset sums $\sum_{a \in S} a$ differ by at least $1$ for all distinct subsets $S \subseteq A$. That is, for any two distinct subsets $S_1, S_2 \subseteq A$, we have $1 \leq |\sum_{a \in S_1} a - \sum_{a \in S_2} a|$. Determine whether there exists a positive real constant $C$ such that for every nonzero natural number $N$ and every finite set $A \subseteq (0, N]$ that is sum-distinct for $N$, the inequality $C \cdot 2^{|A|} < N$ holds.[1]
1Packet records
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Notes and companion material
Original intake status. OPEN as of 2026-07-31. The maintained Erdős Problems database at commit 8138974387d9030542daabe67faaa33eff9356f8 lists Problem 1 as open. The unresolved remainder is the full displayed statement.
- The maintained database entry for Erdős Problem 1 was open at commit 8138974387d9030542daabe67faaa33eff9356f8.
- The pinned Formal Conjectures declaration was matched by problem number and source locator.
- The controlled TheoremDB source corpus was checked for an already published record with the same slug.
How the 2 records connect
ProblemErdős's sum-distinct set problem for real numbers
All 1 recorded relations between these records and the problem
2See also
- Constructing a union from non-cancelling intersectionscombinatorics
- Plane tilings by every five-cell lattice animalcombinatorics
- Cycle Double Cover Conjecturecombinatorics
Contribute to this problem
Cite this problem statement
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“Erdős's sum-distinct set problem for real numbers.” TheoremDB. P2956. Problem statement; statement text SHA-256 fe368e2fab3fbb6da5e18f76618ac1c158bf5afccb64910452984aeb96dcbe3a. https://theoremdb.org/statement/?ref=P2956
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title = {{Erdős's sum-distinct set problem for real numbers}},
howpublished = {TheoremDB},
note = {Problem statement; statement text SHA-256 fe368e2fab3fbb6da5e18f76618ac1c158bf5afccb64910452984aeb96dcbe3a},
url = {https://theoremdb.org/statement/?ref=P2956}
}Plain text: Built Markdown snapshot
This problem includes 2 records joined by 1 typed links, sourced from erdosproblems.com[1], current as of July 31, 2026.
1References
- Packet source. Erdős Problems database, Problem 1, maintained status record. Erdős Problems record 1, checked 2026-08-01. Problem 1; status field and linked bibliography. ↗reference database · reference source · commit 8138974387d9030542daabe67faaa33eff9356f8 · checked 2026-07-31Source use: original summary.Records the current open status and links the literature attached to this exact numbered problem.Also cited at Problem 1; status snapshot 8138974387d9030542daabe67faaa33eff9356f8.Also cited at See dataset.references[0] for the exact external source and locator.Also cited at Editorial research route recorded 2026-07-31.Source used to formulate or check the problem record.Source used to assess the problem's recorded status.For Erdős's sum-distinct set problem for real numbers: Records the current open status and links the literature attached to this exact numbered problem.Source named by the research packet.
- Erdős problem database, data/problems.yaml, commit 8138974387d9030542daabe67faaa33eff9356f8. Problem 1 entry in data/problems.yaml. ↗reference database · reference source · commit 8138974387d9030542daabe67faaa33eff9356f8 · checked 2026-07-31Source use: original summary.Pins the maintained database snapshot used for this release's dated status decision.Source used to assess the problem's recorded status.For Erdős's sum-distinct set problem for real numbers: Pins the maintained database snapshot used for this release's dated status decision.
- Google DeepMind, Formal Conjectures, formal statement for Erdős Problem 1. GitHub commit bb1c69dab14ad895ac1ccdb7b0c0e0a67c8eb3e1. FormalConjectures/ErdosProblems/1.lean:L115; theorem erdos_1.variants.real; commit bb1c69dab14ad895ac1ccdb7b0c0e0a67c8eb3e1. ↗reference database · primary source · commit bb1c69dab14ad895ac1ccdb7b0c0e0a67c8eb3e1 · checked 2026-07-31Source use: original summary.Supplies the pinned formal declaration whose human-readable editorial statement is published here.Source used to assess the problem's recorded status.For Erdős's sum-distinct set problem for real numbers: Supplies the pinned formal declaration whose human-readable editorial statement is published here.
Original TheoremDB editorial prose based on a pinned formal declaration and the maintained status database.
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