Kinship Definition Language

Kinships between persons are specified with letter strings, beginning from the ego and always following a chain of basic relations. For readability, chains may be freely broken into pieces by spaces. Several chains may follow each other separated by commas.
  Chains are case sensitive. Uppercase letters are for individual persons (relative to the preceding person), lowercase letters are modifiers which always follow the person they are concerning to.

  E – ego, the self; may be omitted at the beginning of longer chains, being it the default; this is the only uppercase letter not relative to the preceding person
  P – parent
  S – sibling
  C – child
  M – spouse

Examples
  
  PP – grandparent
  CC – grandchild
  PS – parent’s sibling = aunt or uncle
  PM – parent’s spouse
  CM – child’s spouse

  unspecified – covers any gender
  f – female
  m – male
  i – identical gender to a reference
  o – opposite gender to a reference

Examples
  
  Pf – mother
  PfPm – maternal grandfather
  PSm – uncle
  CP – child’s parent = the ego or the other parent
  PSi – parent’s sibling of the same gender = mother’s sister or father’s brother

  unspecified – covers one person
  a – all persons matching

Examples
  
  PPPma – all great-grandfathers
  PmPPma – all grandfathers of the father

  y – younger than a reference
  e – elder than a reference
  A number after y or e counts that manieth matching person: y2 the second one among the younger ones. This may be followed by a sign: Sy2+ all siblings younger than the 2nd younger sibling, Sy2- all siblings older than this sibling.

Examples
  
  Emy – my younger brother
  PmSfe – father’s elder sister

  s – step
  d – adopted child, adopting parent
  l – lover, life partner (not married)
  k – except myself

A name in () parentheses marks a person for reference: PfPmSfy (Liza) means „let’s call mother’s father’s younger sister Liza”. Before or after this, the same name refers to this person: PPPCay Liza means „all children of the great-great-grandparents younger than Liza”. The name should be separated from any other character by a space.
  A name may stand first in a chain, this makes that person the beginning of the chain, e.g. Liza MPmSfy means „Liza’s spouse’s father’s younger sister”. If Liza wasn’t defined before as a relative to the ego, this defines Liza and provides information about her family tree; it’s good habit to include the name in () parentheses in this case.
  Relative modifiers, if not followed by a person, are relative to the preceding person, e.g. PfSy means „mother’s sibling, younger than mother” while PfSyESfy is „mother’s sibling, younger than my younger sister”.

Any uppercase letter other than those listed above, followed by an = sign and a chain defines a shortcut which can be used later, similar to the original ones.
  Instead of a single letter, a longer string of letters (both uppercase and lowercase) may be used which may even contain any reserved letter, but it must be separated from any neighbouring letter by a space. For instance, MXQ may serve as an abbreviation for maternal cross cousin if we define it. This method may also serve for defining actual terms in a language, e.g. grandfather=PPm.
  A chain starting with E= defines the ego, „my name is”. This may be a name or a chain starting with someone else and leading to the ego. Several definitions of the ego mean changes in point of view, i.e. first we see the situation from either person’s view, then from another person’s eyes.

Examples
  
  A=PfPf – let’s call „maternal grandmother” A
  Liza AM – Liza’s maternal grandmother’s spouse
  E=Liza PmSm – I am Liza’s paternal uncle

A relation may be specified by more than one chain. Since chains may refer to sets of persons (with the a modifier), they may be connected with the following operators:
  
  & – and
  | – or
  ^ – not
  / – another path leading to the same person; after this operator, the starting person is implied to be the same as in the previous chain

They are of equal precedence. If needed, () parentheses may be used to give some operators a greater precedence.

Examples
  
  PPfa | PSfa – a set of all grandmothers and aunts
  So & Ml – someone who is both a sibling of opposite gender and a lover = incestuous, heterosexual relation; actually, Sol means the same
  PmSf / PmPCf – means „father’s sister and father’s parent’s daughter are the same”, what’s true indeed

„Complicated situations” arise when there is a loop on the family tree (if we go back enough and include enough persons there will be loops on any real life family tree). For example, the classic logical riddle about a father who fathered a child with his own daughter. Let’s call them Alice and Bob, and the child Cindy. The following claims will all be true:
  (Alice) Pm (Bob) Cf (Cindy) – Alice’s father is Bob and his daughter is Cindy (this doesn’t tell about the incest yet)
  (Alice) Cf (Cindy) – Alice’s daughter is Cindy
  (Alice) Sf (Cindy) – Alice and Cindy are sisters (both Bob’s daughters)
  (Alice) Cf (Cindy) / Sf (Cindy) – the previous two claims together; note that in the second clue, Alice is implied but not specified
  (Bob) CC (Cindy) – Bob’s granddaughter is Cindy
  (Cindy) SP (Bob) – Cindy’s uncle is Bob

Here comes a listing of relations, first those that have an own term in English, and some more.

Nuclear Family
  
  Mom=Pf
  Dad=Pm
  Parent=P
  Parents=Pa
  Daughter=Cf
  Daughters=Cfa
  Son=Cm
  Sons=Cma
  Child=C
  Children=Ca
  Sister=Sf
  Sisters=Sfa
  Brother=Sm
  Brothers=Sma
  ElderSister=Sfe
  ElderSisters=Sfea
  YoungerSister=Sfy
  YoungerSisters=Sfya
  ElderBrother=Sme
  ElderBrothers=Smea
  YoungerBrother=Smy
  YoungerBrothers=Smya

Aunts and Uncles
  
  ParentsSibling=PS
  MothersSibling=PfS
  MaternalAunt=PfSf
  MaternalUncle=PfSm
  FathersSibling=PmS
  PaternalAunt=PmSf
  PaternalUncle=PmSm
  Aunt=PSf
  Uncle=PSm

First Cousins
  
  Cousin=PSC
  CousinF=PSCf
  CousinM=PSCm
  ElderCousin=PSCe
  ElderCousinF=PSCfe
  ElderCousinM=PSCme
  YoungerCousin=PSCy
  YoungerCousinF=PSCfy
  YoungerCousinM=PSCmy
  CrossCousin=PSoC
  CrossCousinF=PSoCf
  CrossCousinM=PSoCm
  ElderCrossCousin=PSoCe
  ElderCrossCousinF=PSoCfe
  ElderCrossCousinM=PSoCme
  YoungerCrossCousin=PSoCy
  YoungerCrossCousinF=PSoCfy
  YoungerCrossCousinM=PSoCmy
  ParallelCousin=PSiC
  ParallelCousinF=PSiCf
  ParallelCousinM=PSiCm
  ElderParallelCousin=PSiCe
  ElderParallelCousinF=PSiCfe
  ElderParallelCousinM=PSiCme
  YoungerParallelCousin=PSiCy
  YoungerParallelCousinF=PSiCfy
  YoungerParallelCousinM=PSiCmy

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