[CPN] Proposed additions to the PhyloCode (Art. 9)

[de Queiroz, Kevin]

Dear Michel,

The problem is that if "and" is used in this context (qualifying clause), the definition will not function as intended.  For example, if one wants the name Pinnipedia to be inapplicable in the context of phylogenies in which either ursids or mustelids or both taxa are descended from the MRCA of seals, sea lions, and walruses, one must use "or" rather than "and" (Pinnipedia := the smallest crown clade containing seals, sea lions, and walruses, provided that it does not include ursids or mustelids).  If "or" is used, then the name Pinnipedia will not be applicable if either ursids, or mustelids, or both taxa are descended from the MRCA of seals, sea lions, and walruses.  If "and" is used instead, then the name will only be inapplicable if BOTH ursids AND mustelids are descended from the MRCA of seals, sea lions, and walruses.  That is, the definition could result in ursids being included in Pinnipedia, or mustelids being included in Pinnipedia, contrary to the intent of the author.  See the distinction between logical disjunction ("or" operator) and logical conjunction ("and" operator).  

Best,
Kevin

On 6/21/18, 3:20 PM, "CPN on behalf of Michel LAURIN" <cpn-bounces at listserv.ohio.edu on behalf of michel.laurin at mnhn.fr> wrote:

    Dear all,
    
    I generally agree with the changes, but I find this part problematic:
    
    "For example, it would be
    appropriate to use “or” when using a minimum-clade definition with multiple
    external specifiers, including those used in qualifying clauses, to render the defined
    name inapplicable in the context of phylogenetic hypotheses in which any one (or
    more) of the external specifiers is more closely related to some of the internal
    specifiers than those internal specifiers are to other internal specifiers (see Art.
    11.12, Example 1)."
    
    I do not find obvious that using "or" in this context should be interpreted in this way. I think that if we keep this text, more explanation, not in a note, is in order. I interpret the "or" as leading to ambiguity in interpretation and I would simply discourage (perhaps forbid) it.
    
    Best wishes,
    
    Michel
    
    ----- Mail original -----
    De: "Philip Cantino" <cantino at ohio.edu>
    À: "Committee on Phylogenetic Nomenclature" <cpn at listserv.ohio.edu>
    Cc: "Max Langer" <mclanger at ffclrp.usp.br>
    Envoyé: Lundi 18 Juin 2018 17:58:27
    Objet: [CPN] Proposed additions to the PhyloCode (Art. 9)
    
    Dear CPN members,
    
    Kevin and I are proposing the attached additions to Article 9 to clarify points of confusion that we became aware of in the process of editing Phylonyms contributions.  These are probably the last changes in the code that we will propose before the manuscript is finalized. 
    
    If you have comments or questions, please send them to the listserv by June 30.  If there is no ongoing discussion at that point, I will call for a vote.   Please do not vote yet, in case there is discussion before June 30.
    
    Best regards,
    Phil
    
    
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