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mostly trivial doc fixes on partition.py
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darijgr committed Dec 27, 2013
1 parent 6812b87 commit b36286f
Showing 1 changed file with 28 additions and 18 deletions.
46 changes: 28 additions & 18 deletions src/sage/combinat/partition.py
Expand Up @@ -245,7 +245,8 @@
sage: Partitions().from_zero_one([1, 1, 1, 1, 0, 1, 0])
[5, 4]
sage: all(Partitions().from_zero_one(mu.zero_one_sequence()) == mu for n in range(5) for mu in Partitions(n))
sage: all(Partitions().from_zero_one(mu.zero_one_sequence())
....: == mu for n in range(5) for mu in Partitions(n))
True
We can compute the Frobenius coordinates and go back and forth::
Expand All @@ -254,8 +255,8 @@
([6, 1], [2, 0])
sage: Partition(frobenius_coordinates=([6,1],[2,0]))
[7, 3, 1]
sage: all(mu == Partition(frobenius_coordinates=mu.frobenius_coordinates()) for n in range(30)\
for mu in Partitions(n))
sage: all(mu == Partition(frobenius_coordinates=mu.frobenius_coordinates())
....: for n in range(30) for mu in Partitions(n))
True
We use the lexicographic ordering::
Expand Down Expand Up @@ -479,10 +480,14 @@ class Partition(CombinatorialObject, Element):
non-increasing list of positive integers (the *parts* of the
partition) with total sum `n`.
A partition is often representation by a diagram consisting of **cells**,
or **boxes**, placed in rows on top of each other with the number of cells
in the `i^{th}` row, reading from top to bottom, is the `i^{th}` part of
the partition.
A partition is often represented as a diagram consisting of **cells**,
or **boxes**, placed in rows on top of each other such that the number of
cells in the `i^{th}` row, reading from top to bottom, is the `i^{th}`
part of the partition. The rows are left-justified (and become shorter
and shorter the farther down one goes). This diagram is called the
**Young diagram** of the partition, or more precisely its Young diagram
in English notation. (French and Russian notations are variations on this
representation.)
The coordinate system related to a partition applies from the top
to the bottom and from left to right. So, the corners of the
Expand Down Expand Up @@ -1869,7 +1874,8 @@ def generalized_pochhammer_symbol(self, a, alpha):

def get_part(self, i, default=Integer(0)):
r"""
Return the `i^{th}` part of self, or ``default`` if it does not exist.
Return the `i^{th}` part of ``self``, or ``default`` if it does
not exist.
EXAMPLES::
Expand Down Expand Up @@ -4122,7 +4128,7 @@ def jacobi_trudi(self):
"""
Return the Jacobi-Trudi matrix of ``self`` thought of as a skew
partition. See :meth:`SkewPartition.jacobi_trudi()
<sage.combinat.skew_partition.SkewPartition_class.jacobi_trudi>`.
<sage.combinat.skew_partition.SkewPartition.jacobi_trudi>`.
EXAMPLES::
Expand Down Expand Up @@ -4203,15 +4209,16 @@ def character_polynomial(self):

def dimension(self, smaller = [], k = 1):
r"""
This function computes the number of paths from the
``smaller`` partition to the partition ``self``, where each step
consists of adding a `k`-ribbon while keeping a partition.
Return the number of paths from the ``smaller`` partition to
the partition ``self``, where each step consists of adding a
`k`-ribbon while keeping a partition.
Note that a 1-ribbon is just a single cell, so this gives path
lengths in the Young graph when `k = 1`.
Note that a 1-ribbon is just a single cell, so this counts paths
in the Young graph when `k = 1`.
Note also that the defaut case (`k = 1` and ``smaller = []``) gives the
dimension of characters of the symmetric groups.
Note also that the default case (`k = 1` and ``smaller = []``)
gives the dimension of the irreducible representation of the
symmetric group corresponding to ``self``.
INPUT:
Expand Down Expand Up @@ -4259,13 +4266,16 @@ def dimension(self, smaller = [], k = 1):
A check coming from the theory of `k`-differentiable posets::
sage: k=2; core = Partition([2,1])
sage: all(sum(mu.dimension(core,k=2)^2 for mu in Partitions(3+i*2) if mu.core(2) == core)==2^i*factorial(i) for i in range(10))
sage: all(sum(mu.dimension(core,k=2)^2
....: for mu in Partitions(3+i*2) if mu.core(2) == core)
....: == 2^i*factorial(i) for i in range(10))
True
Checks that the dimension satisfies the obvious recursion relation::
sage: test = lambda larger, smaller: larger.dimension(smaller) == sum(mu.dimension(smaller) for mu in larger.down())
sage: all(test(larger,smaller) for l in xrange(1,10) for s in xrange(0,10) for larger in Partitions(l) for smaller in Partitions(s) if smaller!=larger)
sage: all(test(larger,smaller) for l in xrange(1,10) for s in xrange(0,10)
....: for larger in Partitions(l) for smaller in Partitions(s) if smaller != larger)
True
ALGORITHM:
Expand Down

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