Can we teach logic reasoners to correctly apply nomenclatural rules?
No, this not concept taxonomy. Instead this post is intended to set up a nomenclaturally and taxonomically correct use case for an Answer Set Programming (ASP) reasoning project. The post will limit itself to: (1) getting the required nomenclatural emendations “right” (Section 4), given (2) a specific set of starting conditions (Sections 1 & 2), and (3) a new taxonomic insight that necessitates change (Section 3).
1. Starting conditions
This is a zoological use case (ICZN). The year is 2000. The family Agenidae contains one subfamily, two tribes, four genera, and 12 species, totalling 20 published names, as detailed below (Figure 1). The respective years of publication for the ranked names are provided, ranging from 1775 to 1985. * indicates Priority at the relevant rank. This leads to “Priority chains” such as  –  –  –  –  based on the designation of A. primus, 1775*. The four species-level type names were published from 1775-1790; all non-type species-level names are younger (20th century).
All 12 species represent taxonomically distinct, valid taxa. Each of the type species (and name) has a type specimen whose “apparent” morphology – square (primus), rectangle (secundus), hemiellipse (tertius), and pentagon (quartus) – serves to anchor the circumscription of the entailing genus (up to tribe, subfamily, and family – where applicable). “Apparent” in preceding phrase means that at the original time of publication (1775-1790, respectively), the type specimens were asserted to have these properties. The younger species types were classified accordingly; e.g.  and  have type specimens that exhibit a square, hence they were assigned to Agenus, 1775*.
2. Complication – some type specimens are not what they seem(ed)
Notice that in Figure 1, each of the four oldest type specimens is somehow “compromised”, as represented by a grey circle that (symbolically) interferes with an unambiguous recognition of their morphology (or molecular identity, for that matter). The details are not relevant – the general point is that specific interpretations of the types’ morphological identities were made at the original times of publication (1775-1790); yet now (in the year 2000) it is evident that these assertions of morphology were in error.
3. Change scenario 1 – the type specimen of Agenus primus is rectangular
One particular change scenario following re-examination of type specimens in 2000 is shown in Figure 2. Accordingly, the type specimen of A. primus, 1775* is no longer considered to have a square morphology (!); instead exhibiting a rectangular morphology (green rectangle) that also characterizes the type specimen of E. secundus, 1780* – with additional nomenclatural and taxonomic contingencies (see Section 4). All other type specimens are “resolved” to exhibit the properties as originally asserted (hence no grey circles are shown for secundus, tertius, and quartus).
4. Nomenclatural consequences
In this particular change scenario, the type species name primus has “global” Priority. It cannot be moved into synonymy of any other (and necessarily younger) name. Hence:
- E. secundus => A. secundus, new placement, new combination
- E. septimus => A. septimus, new placement, new combination
- E. octavus => A. octavus, new placement, new combination
- Egenus => new synonym of Agenus, genus level
- Novagenus => new genus name, child of Agenini *
- Novagenus quintus => new combination
- Novagenus quintus => new type designation for Novagenus
- Novagenus sextus =>new combination
* The prefix Nov- is chosen arbitrarily; the main point is that a new genus name is needed to accommodate  and .
5. Other change scenarios
Thirty-six such scenarios are possible if (1) all species-level taxa remain valid and (2) only one taxon is “moved”.