Quarterly report pursuant to Section 13 or 15(d)

Stock Options and Warrants (Detail)

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Stock Options and Warrants (Detail) - USD ($)
 6 Months Ended 12 Months Ended
Nov. 30, 2017
May 31, 2017
Stock option and warrant activity    
Options and warrants outstanding, Number of Shares 77,859,626  
Granted, Number of Shares 16,497,852  
Exercised, Number of Shares (3,295,000)  
Forfeited/expired/cancelled, Number of Shares (3,510,677)  
Options and warrants outstanding, Number of Shares 87,551,801 77,859,626
Outstanding exercisable, Number of Shares 83,426,884  
Options and warrants outstanding, Weighted Average Exercise Price $ 0.86  
Granted, Weighted Average Exercise Price 0.78  
Exercised, Weighted Average Exercise Price 0.50  
Forfeited/expired/cancelled, Weighted Average Exercise Price 0.98  
Options and warrants outstanding, Weighted Average Exercise Price 0.83 $ 0.86
Outstanding exercisable, Weighted Average Exercise Price $ 0.83  
Options and warrants outstanding, Weighted Average Remaining Contractual Life 3 years 6 months 3 days 3 years 4 months 24 days
Outstanding exercisable, Weighted Average Remaining Contractual Life 3 years 2 months 30 days  
Options and warrants outstanding, Aggregate Intrinsic Value $ 70,500 $ 40,250
Outstanding exercisable, Aggregate Intrinsic Value $ 37,750