The ornamental design for a chair, as shown and described.
FIG. 1 is a front perspective view from above and to one side of a chair
showing a first embodiment of my design;
FIG. 2 is a rear perspective view from below corresponding to FIG. 1;
FIG. 3 is a view similar to FIG. 1 showing a second embodiment of my design
which is the same as the embodiments of FIGS. 1 and 2 except for the
omission of perforations in the seat and back;
FIG. 4 is a front perspective view from one side and above of a chair
according to a third embodiment of my design;
FIG. 5 is a rear perspective view from below corresponding to FIG. 4.
A fourth embodiment of my design (not shown) would be the same as the chair
of FIGS. 4 and 5 but without the perforations in the seat and back.