Add lemmas for ex2
Add lemmas for ex2

gares/coq,silene/coq,ppedrot/coq,ejgallego/coq,amintimany/coq,gares/coq,amintimany/coq,amintimany/coq,JasonGross/coq,maximedenes/coq,Matafou/coq,ejgallego/coq,ppedrot/coq,silene/coq,JasonGross/coq,letouzey/coq-wip,ejgallego/coq,SkySkimmer/coq,coq/coq,ppedrot/coq,gares/coq,SkySkimmer/coq,william-lawvere/coq,silene/coq,Zimmi48/coq,letouzey/coq-wip,coq/coq,coq/coq,william-lawvere/coq,ppedrot/coq,gares/coq,letouzey/coq-wip,coq/coq,JasonGross/coq,Matafou/coq,Zimmi48/coq,letouzey/coq-wip,SkySkimmer/coq,Zimmi48/coq,Matafou/coq,Zimmi48/coq,maximedenes/coq,SkySkimmer/coq,william-lawvere/coq,maximedenes/coq,gares/coq,ejgallego/coq,maximedenes/coq,ppedrot/coq,letouzey/coq-wip,maximedenes/coq,JasonGross/coq