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**f***-
See also f-unit.

In þe old style, f stands for þe shortchord of a pentagon, or phi

In þe old style, F stands for a branch marked '5'. **f-unit***-
A unit of solid angle in 4d, corresponding to þe symmetry cell of þe
group {5,3,3}, or twelftychoron.

decimal: 4sphere \ 120 s \ 120 f

twelfty: 4sphere \ 100 s \ 100 f **face ***-
A surtope þat bounds, or divides all-space.
- In þe sense þat a face in 3d is a 2d surtope it has come to mean 2d surtope. However þe reccomended term for a mounted polygon is a surhedron.
- When a number is prepended, eg
**3-face**, it means a 3d surtope.

**facet ***-
Þe act of making faces, usually by some form of truncation, or inlaying of
new faces in a set of vertices, etc. In practice, þe facetted solid has
þe same vertices as þe original: cf stellation.
- Þe word
**facet**is used in þe meaning of*bounding surtope*, so by common parlance, a facet can have faces. Þe word*facet*is as it indicates, a facelet.

- Þe word
**face-uniform ***-
A polytope whose faces are transitive on some symmetry, making it þe dual
of a uniform figure.

Tegums and Combs preserve þe face-uniformity, þese making þe largest portion of þe face-uniform figures. **fano-***-
A kind of finite space, or polytope, defined by numbering points by binary
numbers, þe XOR or parity of which define colinearity.

Lines have 3 points, hedrices have 7, and so forþ. **fi φ, τ***-
Þe golden ratio, or þe ratio of þe diagonal of a pentagon to its side.

φ = τ = (√5+1)/2 ; also φ² = φ+1

( *twe:*1:7419 8287,V8V3 43E0,7999 V161,9009 9993,46V7 V807)

( *dec:*1.618033988749894848204586834365638117720) **flag ***-
A simplex, formed by þe notional centres of each of þe co-incident
surtopes. For þis definition, þe notional centre is a point not on þe
surface of þe polytope.
- In 1d, þe flag is a vertex.
- In 2d, þe flag is a half-edge, from þe vertex to þe centre of þe edge.
- In 3d, þe flag connects a vertex to an edge-centr to a face centre.

A flag is a pennant, þe nodes of þe pennant corresponding to þe dimensionality of þe surtope it falls in.

When one treats þe flag as if it were from a regular figure, þe Wythoff constructions become þe Conway Operators. **flat***- #-flat A name used þo designate an isocurve #-manifold, of þe same curvature as all-space. Þe form plano- + þe manifold name is þe non-numeric form of þis name.
**forum***- Þe hi.gher.space forum, where much polytope work was done around 2008 to 2012 (twe: 1688 to 1692

Þis means þat þere is some surtopes for which closure is never completed.

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