Intereting Posts

How to show that the modulus of $\frac{z-w}{1-\bar{z}w}$ is always $1$?
Real Analysis – A sequence that has no convergent subsequence
How to prove that a topological space is connected iff it has exactly two clopen subsets?
A complex map with “bounded” derivative is injective
The security guard problem
For which complex $a,\,b,\,c$ does $(a^b)^c=a^{bc}$ hold?
Importance of rigor
Is this a correct/good way to think interpret differentials for the beginning calculus student?
Prove that formula in monadic second order logic exists – for each node path is finite
Associativity of Day convolution
Show that $\lim_{n \rightarrow \infty} \frac{\sin^{n}(\frac{x}{\sqrt{n}})}{\left(\frac{x}{\sqrt{n}} \right)^n} = e^{-\frac{x^2}{6}} $
Floating point arithmetic: $(x-2)^9$
Are there any non-trivial group extensions of $SU(N)$?
Question about the proof of $S^3/\mathbb{Z}_2 \cong SO(3)$
Is $n \sin n$ dense on the real line?

What do we call those well-founded posets $P$ with the property that for every $x \in P$, all maximal chains in the lowerset generated by $x$ have the same length? Examples:

- The set of all finite subsets of a (possibly infinite) set.
- The set of all finite-dimensional vector subspaces of a (possibly infinite-dimensional) vector space.
- The set of all finite-dimensional affine subspaces a (possibly infinite-dimensional) affine space.
- Any set-theoretic tree.
- Any poset that could reasonably be construed as an “abstract polytope.”

- Number of $(0,1)$ $m\times n$ matrices with no empty rows or columns
- Express $1 + \frac {1}{2} \binom{n}{1} + \frac {1}{3} \binom{n}{2} + \dotsb + \frac{1}{n + 1}\binom{n}{n}$ in a simplifed form
- Prove an identity in a Combinatorics method
- How many tries to get at least k successes?
- Probability distribution in the coupon collector's problem
- How many planar arrangements of $n$ circles?
- Combinatorial proofs: having a difficult time understanding how to write them out
- A polynomial sequence
- How many injective functions $f:\to{}$ has no fixed point? $(m\le n)$
- Prove combinatorics identity

I think this paper gives the definition you want, if I understand you correctly:

Definition 2.9. A poset $P$ will be called

locally rankedif all its principal lower ideals are ranked.

- Stirling's Approximation for binomial coefficient
- How to show $\sum_{k=n}^\infty{\frac{1}{k!}} \leq \frac{2}{n!}$
- Using SVDs to prove $C(XX^{\prime}) = C(X)$
- $\sup\{g(y):y\in Y\}\leq \inf\{f(x):x\in X\}$
- How to write an integral as a limit?
- Every two positive integers are related by a composition of these two functions?
- S4/V4 isomorphic to S3 – Understanding Attached Tables
- Inverse of Symmetric Matrix Plus Diagonal Matrix if Square Matrix's Inverse Is Known
- Sobolev spaces and integrability of Fourier transforms
- What does it mean for something to be true but not provable in peano arithmetic?
- An exercise in Liu regarding a sheaf of ideals (Chapter II 3.4)
- Show $x^6 + 1.5x^5 + 3x – 4.5$ is irreducible in $\mathbb Q$.
- Define second derivative ($f''$) without using first derivative ($f'$)
- Find all the numbers $n$ such that $\frac{12n-6}{10n-3}$ can't be reduced.
- Finding the derivative of the norm