2.1 Formal properties of the CoGesT 1.0 notation

In CoGesT 1.0 the notation for gestures can be formalised as feature vectors. A number of properties of the notation are useful for transcribers but need to be further regularised for computational purposes. As a first step, a slightly different set of distinctions as compared with the original CoGesT 1.0 account are introduced:

Simplex gesture:

A gesture which is not further analysed into component gestures and is described with a feature vector.

The final vector element in the current CoGest 1.0 conventions contains the values rp, or lp, sy, pa, which are not actually properties of the gesture itself but (see discussion below) either names of the left or right body member objects (typically hands) which have these properties (rp, lp) or represent macros which abbreviate the second gesture of a left-right pair (sy, pa). This position in the CoGesT 1.0 vectors is replaced in the following representations by ``_''.

A further distinction among the simplex gestures will be made as follows:

3-place static gesture:

A gesture with no movement of a body member object.

The static gestures include hold and posture cases: [15m,0B,_]

11-place dynamic gesture:

A gesture with movement of a body member object.

All other gestures involving Source, Trajectory and Target have the structure [11r,5C,do/ba,ar,0B,m,r(0),me,15m,5A,_]; the 3rd position (for direction) is itself a 1-place, 2-place or 3-place vector (see discussion below).

Compound gesture:

Gesture which has gestures as its component parts.

Simultaneous compound gesture:

A compound gesture consisting of two or more gestures in a relation of temporal overlap (i.e. complete or partial simultaneity).

Gestures by a body member typically do not occur alone, but enter into temporally concurrent relations with other body members - hands with each other, hands with head, lap, etc. CoGesT 1.0 representations are concerned only with simultaneous hand gestures.

The basic type of compound gesture dealt with in CoGesT 1.0 is a special case of simultaneous compound gesture, the gesture pair, performed by mirrored body member objects, typically the hands.

The link between elements of a hand gesture pair is denoted by ``;''. The combination of two gestures with ``;'' will be termed a gesture pair. The combined arity of the two vectors in a pair is thus either 6 (for a static simplex gesture pair), 11 (for a dynamic simplex gesture pair), 14 (for a static and a dynamic gesture pair) or 22 (for a dynamic simplex gesture pair where the simplex gestures are independent of each other).

Sequential compound gesture:

A compound gesture consisting of two or more gestures in a relation of temporal precedence.

In CoGesT 1.0, gesture pairs may be concatenated into cohesive sequences, the complex gestures of the original CoGesT 1.0 description; in CoGesT 1.0 concatenation is represented by juxtaposition. An example of a sequential compound gesture is a cohesive sequence of pointing gestures denoting elements of a set of related objects.

Complex compound gesture:

A compound gesture consisting of three or more gestures in relations of temporal precedence and temporal overlap.

The complex compound gesture contains less constrained structures than the relatively straightforward concatenation of gesture pairs.

These structures correspond to the lattices defined within the Annotation Graph framework (cf. Bird and Liberman (2001)). An issue which is not addressed in the present report is the need for further explicating the notion of simultaneity or temporal overlap, for instance