FIG. 1 illustrates a front view of the claimed design for a bagel slicer;
FIG. 2 illustrates a top view thereof;
FIG. 3 illustrates a bottom view thereof;
FIG. 4 illustrates an internal sectional view thereof;
FIG. 5 illustrates a bottom perspective view thereof; and,
FIG. 6 illustrates a top perspective view thereof.