The Alfred G. Vanderbilt Handicap is an American Thoroughbred horse race held annually near the end of July at Saratoga Race Course in Saratoga Springs, New York. A Grade I event open to horses age three and older, it is a six furlong sprint raced on dirt.
Horses participate in the Alfred G. Vanderbilt Handicap race annually.
The statement is indeed neither definitely correct nor definitely incorrect because the context does not say "horses participated". The context does say "the event is open to horses" and that the event is "held annually". However, it does not explicitly say that people who own horses enroll their horses to participate in the event annually.
( z1 participate :ARG0 ( z2 horse ) :ARG1 ( z3 race :ARG3 ( z4 event :name ( z5 name :op "Alfred" :op "G." :op "Vanderbilt" :op "Handicap" ) ) :frequency ( z6 rate-entity :ARG3 ( z7 temporal-quantity :quant 1 :unit ( z8 year ) ) ) ) )